# Mail::Message - man - phpMan

## NAME
    [Mail::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage/markdown) - general message object

## INHERITANCE
     [Mail::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage/markdown) has extra code in
       [Mail::Message::Construct](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AConstruct/markdown)
       [Mail::Message::Construct::Bounce](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AConstruct%3A%3ABounce/markdown)
       [Mail::Message::Construct::Build](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AConstruct%3A%3ABuild/markdown)
       [Mail::Message::Construct::Forward](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AConstruct%3A%3AForward/markdown)
       [Mail::Message::Construct::Read](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AConstruct%3A%3ARead/markdown)
       [Mail::Message::Construct::Rebuild](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AConstruct%3A%3ARebuild/markdown)
       [Mail::Message::Construct::Reply](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AConstruct%3A%3AReply/markdown)
       [Mail::Message::Construct::Text](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AConstruct%3A%3AText/markdown)

     [Mail::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage/markdown)
       is a [Mail::Reporter](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AReporter/markdown)

     [Mail::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage/markdown) is extended by
       [Mail::Box::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3ABox%3A%3AMessage/markdown)
       [Mail::Message::Dummy](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3ADummy/markdown)
       [Mail::Message::Part](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3APart/markdown)
       [Mail::Message::Replace::MailInternet](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AReplace%3A%3AMailInternet/markdown)

## SYNOPSIS
     use [Mail::Box::Manager](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3ABox%3A%3AManager/markdown);
     my $mgr    = [Mail::Box::Manager](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3ABox%3A%3AManager/markdown)->new;
     my $folder = $mgr->open(folder => 'InBox');
     my $msg    = $folder->[message(2)](https://www.chedong.com/phpMan.php/man/message/2/markdown);    # $msg is a [Mail::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage/markdown) now

     my $subject = $msg->subject;         # The message's subject
     my @cc      = $msg->cc;              # List of [Mail::Address](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AAddress/markdown)'es

     my [Mail::Message::Head](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AHead/markdown) $head = $msg->head;
     my [Mail::Message::Body](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3ABody/markdown) $body = $msg->decoded;
     $msg->decoded->print($outfile);

     # Send a simple email
     [Mail::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage/markdown)->build
       ( To             => '<you@example.com>'
       , From           => '<me@example.com>'
       , Subject        => "My subject"
       , data           => "Some plain text content"
       )->send(via => 'postfix');

     my $reply_msg = [Mail::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage/markdown)->reply(...);
     my $frwd_msg  = [Mail::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage/markdown)->forward(...);

## DESCRIPTION
    A "[Mail::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage/markdown)" object is a container for MIME-encoded message
    information, as defined by RFC2822. Everything what is not specificaly
    related to storing the messages in mailboxes (folders) is implemented in
    this class. Methods which are related to folders is implemented in the
    [Mail::Box::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3ABox%3A%3AMessage/markdown) extension.

    The main methods are get(), to get information from a message header
    field, and decoded() to get the intended content of a message. But there
    are many more which can assist your program.

    Complex message handling, like construction of replies and forwards, are
    implemented in separate packages which are autoloaded into this class.
    This means you can simply use these methods as if they are part of this
    class. Those package add functionality to all kinds of message objects.

    Extends "DESCRIPTION" in [Mail::Reporter](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AReporter/markdown).

## METHODS
    Extends "METHODS" in [Mail::Reporter](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AReporter/markdown).

### Constructors
    Extends "Constructors" in [Mail::Reporter](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AReporter/markdown).

    $obj->clone(%options)
        Create a copy of this message. Returned is a "[Mail::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage/markdown)" object.
        The head and body, the log and trace levels are taken. Labels are
        copied with the message, but the delete and modified flags are not.

        BE WARNED: the clone of any kind of message (or a message part) will
        always be a "[Mail::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage/markdown)" object. For example, a
        [Mail::Box::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3ABox%3A%3AMessage/markdown)'s clone is detached from the folder of its
        original. When you use [Mail::Box::addMessage](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3ABox%3A%3AaddMessage/markdown)() with the cloned
        message at hand, then the clone will automatically be coerced into
        the right message type to be added.

        See also [Mail::Box::Message::copyTo](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3ABox%3A%3AMessage%3A%3AcopyTo/markdown)() and
        [Mail::Box::Message::moveTo](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3ABox%3A%3AMessage%3A%3AmoveTo/markdown)().

         -Option      --Default
          shallow       <false>
          shallow_body  <false>
          shallow_head  <false>

        shallow => BOOLEAN
          When a shallow clone is made, the header and body of the message
          will not be cloned, but shared. This is quite dangerous: for
          instance in some folder types, the header fields are used to store
          folder flags. When one of both shallow clones change the flags,
          that will update the header and thereby be visible in both.

          There are situations where a shallow clone can be used safely. For
          instance, when [Mail::Box::Message::moveTo](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3ABox%3A%3AMessage%3A%3AmoveTo/markdown)() is used and you are
          sure that the original message cannot get undeleted after the
          move.

        shallow_body => BOOLEAN
          A rather safe bet, because you are not allowed to modify the body
          of a message: you may only set a new body with body().

        shallow_head => BOOLEAN
          Only the head uses is reused, not the body. This is probably a bad
          choice, because the header fields can be updated, for instance
          when labels change.

        example:

         $copy = $msg->clone;

    [Mail::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage/markdown)->new(%options)
         -Option    --Defined in     --Default
          body                         undef
          body_type                    [Mail::Message::Body::Lines](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3ABody%3A%3ALines/markdown)
          deleted                      <false>
          field_type                   undef
          head                         undef
          head_type                    [Mail::Message::Head::Complete](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AHead%3A%3AComplete/markdown)
          labels                       {}
          log         [Mail::Reporter](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AReporter/markdown)   'WARNINGS'
          messageId                    undef
          modified                     <false>
          trace       [Mail::Reporter](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AReporter/markdown)   'WARNINGS'
          trusted                      <false>

        body => OBJECT
          Instantiate the message with a body which has been created
          somewhere before the message is constructed. The OBJECT must be a
          sub-class of [Mail::Message::Body](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3ABody/markdown). See also body() and storeBody().

        body_type => CLASS
          Default type of body to be created for readBody().

        deleted => BOOLEAN
          Is the file deleted from the start?

        field_type => CLASS
        head => OBJECT
          Instantiate the message with a head which has been created
          somewhere before the message is constructed. The OBJECT must be a
          (sub-)class of [Mail::Message::Head](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AHead/markdown). See also head().

        head_type => CLASS
          Default type of head to be created for readHead().

        labels => ARRAY|HASH
          Initial values of the labels. In case of [Mail::Box::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3ABox%3A%3AMessage/markdown)'s,
          this shall reflect the state the message is in. For newly
          constructed [Mail::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage/markdown)'s, this may be anything you want,
          because coerce() will take care of the folder specifics once the
          message is added to one.

        log => LEVEL
        messageId => STRING
          The id on which this message can be recognized. If none specified
          and not defined in the header --but one is needed-- there will be
          one assigned to the message to be able to pass unique message-ids
          between objects.

        modified => BOOLEAN
          Flags this message as being modified from the beginning on.
          Usually, modification is auto-detected, but there may be reasons
          to be extra explicit.

        trace => LEVEL
        trusted => BOOLEAN
          Is this message from a trusted source? If not, the content must be
          checked before use. This checking will be performed when the body
          data is decoded or used for transmission.

### Constructing a message
    $obj->bounce( [<$rg_object|%options>] )
        Inherited, see "Constructing a message" in
        [Mail::Message::Construct::Bounce](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AConstruct%3A%3ABounce/markdown)

    [Mail::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage/markdown)->build( [$message|$part|$body], $content )
        Inherited, see "Constructing a message" in
        [Mail::Message::Construct::Build](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AConstruct%3A%3ABuild/markdown)

    [Mail::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage/markdown)->buildFromBody($body, [$head], $headers)
        Inherited, see "Constructing a message" in
        [Mail::Message::Construct::Build](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AConstruct%3A%3ABuild/markdown)

    $obj->forward(%options)
        Inherited, see "Constructing a message" in
        [Mail::Message::Construct::Forward](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AConstruct%3A%3AForward/markdown)

    $obj->forwardAttach(%options)
        Inherited, see "Constructing a message" in
        [Mail::Message::Construct::Forward](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AConstruct%3A%3AForward/markdown)

    $obj->forwardEncapsulate(%options)
        Inherited, see "Constructing a message" in
        [Mail::Message::Construct::Forward](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AConstruct%3A%3AForward/markdown)

    $obj->forwardInline(%options)
        Inherited, see "Constructing a message" in
        [Mail::Message::Construct::Forward](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AConstruct%3A%3AForward/markdown)

    $obj->forwardNo(%options)
        Inherited, see "Constructing a message" in
        [Mail::Message::Construct::Forward](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AConstruct%3A%3AForward/markdown)

    $obj->forwardPostlude()
        Inherited, see "Constructing a message" in
        [Mail::Message::Construct::Forward](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AConstruct%3A%3AForward/markdown)

    $obj->forwardPrelude()
        Inherited, see "Constructing a message" in
        [Mail::Message::Construct::Forward](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AConstruct%3A%3AForward/markdown)

    $obj->forwardSubject(STRING)
        Inherited, see "Constructing a message" in
        [Mail::Message::Construct::Forward](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AConstruct%3A%3AForward/markdown)

    [Mail::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage/markdown)->read($fh|STRING|SCALAR|ARRAY, %options)
        Inherited, see "Constructing a message" in
        [Mail::Message::Construct::Read](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AConstruct%3A%3ARead/markdown)

    $obj->rebuild(%options)
        Inherited, see "Constructing a message" in
        [Mail::Message::Construct::Rebuild](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AConstruct%3A%3ARebuild/markdown)

    $obj->reply(%options)
        Inherited, see "Constructing a message" in
        [Mail::Message::Construct::Reply](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AConstruct%3A%3AReply/markdown)

    $obj->replyPrelude( [STRING|$field|$address|ARRAY-$of-$things] )
        Inherited, see "Constructing a message" in
        [Mail::Message::Construct::Reply](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AConstruct%3A%3AReply/markdown)

    $obj->replySubject(STRING)
    [Mail::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage/markdown)->replySubject(STRING)
        Inherited, see "Constructing a message" in
        [Mail::Message::Construct::Reply](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AConstruct%3A%3AReply/markdown)

### The message
    $obj->container()
        If the message is a part of another message, "container" returns the
        reference to the containing body.

        example:

         my [Mail::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage/markdown) $msg = ...
         return unless $msg->body->isMultipart;
         my $part   = $msg->body->[part(2)](https://www.chedong.com/phpMan.php/man/part/2/markdown);

         return unless $part->body->isMultipart;
         my $nested = $part->body->[part(3)](https://www.chedong.com/phpMan.php/man/part/3/markdown);

         $nested->container;  # returns $msg->body
         $nested->toplevel;   # returns $msg
         $msg->container;     # returns undef
         $msg->toplevel;      # returns $msg
         $msg->isPart;        # returns false
         $part->isPart;       # returns true

    $obj->isDummy()
        Dummy messages are used to fill holes in linked-list and such, where
        only a message-id is known, but not the place of the header of body
        data.

        This method is also available for [Mail::Message::Dummy](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3ADummy/markdown) objects,
        where this will return "true". On any extension of "[Mail::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage/markdown)",
        this will return "false".

    $obj->isPart()
        Returns true if the message is a part of another message. This is
        the case for [Mail::Message::Part](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3APart/markdown) extensions of "[Mail::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage/markdown)".

    $obj->messageId()
        Retrieve the message's id. Every message has a unique message-id.
        This id is used mainly for recognizing discussion threads.

    $obj->partNumber()
        Returns a string representing the location of this part. In case the
        top message is a single message, 'undef' is returned. When it is a
        multipart, '1' up to the number of multiparts is returned. A
        multi-level nested part may for instance return '2.5.1'.

        Usually, this string is very short. Numbering follows the IMAP4
        design, see RFC2060 section 6.4.5.

    $obj->print( [$fh] )
        Print the message to the FILE-HANDLE, which defaults to the selected
        filehandle, without the encapsulation sometimes required by a folder
        type, like write() does.

        example:

         $message->print(\*STDERR);  # to the error output
         $message->print;            # to the selected file

         my $out = [IO::File](https://www.chedong.com/phpMan.php/perldoc/IO%3A%3AFile/markdown)->new('out', 'w');
         $message->print($out);      # no encapsulation: no folder
         $message->write($out);      # with encapsulation: is folder.

    $obj->send( [$mailer], %options )
        Transmit the message to anything outside this Perl program. Returns
        false when sending failed even after retries.

        The optional $mailer is a [Mail::Transport::Send](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3ATransport%3A%3ASend/markdown) object. When the
        $mailer is not specified, one will be created and kept as default
        for the next messages as well.

        The %options are mailer specific, and a mixture of what is usable
        for the creation of the mailer object and the sending itself.
        Therefore, see for possible options [Mail::Transport::Send::new](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3ATransport%3A%3ASend%3A%3Anew/markdown)() and
        [Mail::Transport::Send::send](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3ATransport%3A%3ASend%3A%3Asend/markdown)(). That object also provides a
        "trySend()" method which gives more low-level control.

        example:

         $message->send;

        is short (but little less flexibile) for

         my $mailer = [Mail::Transport::SMTP](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3ATransport%3A%3ASMTP/markdown)->new(@smtpopts);
         $mailer->send($message, @sendopts);

        See examples/send.pl in the distribution of [Mail::Box](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3ABox/markdown).

        example:

         $message->send(via => 'sendmail')

    $obj->size()
        Returns an estimated size of the whole message in bytes. In many
        occasions, the functions which process the message further, for
        instance send() or print() will need to add/change header lines or
        add CR characters, so the size is only an estimate with a few
        percent margin of the real result.

        The computation assumes that each line ending is represented by one
        character (like UNIX, MacOS, and sometimes Cygwin), and not two
        characters (like Windows and sometimes Cygwin). If you write the
        message to file on a system which uses CR and LF to end a single
        line (all Windows versions), the result in that file will be at
        least nrLines() larger than this method returns.

    $obj->toplevel()
        Returns a reference to the main message, which will be the current
        message if the message is not part of another message.

    $obj->write( [$fh] )
        Write the message to the FILE-HANDLE, which defaults to the selected
        $fh, with all surrounding information which is needed to put it
        correctly in a folder file.

        In most cases, the result of "write" will be the same as with
        print(). The main exception is for Mbox folder messages, which will
        get printed with their leading 'From ' line and a trailing blank.
        Each line of their body which starts with 'From ' will have an '>'
        added in front.

### The header
    $obj->bcc()
        Returns the addresses which are specified on the "Bcc" header line
        (or lines) A list of [Mail::Address](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AAddress/markdown) objects is returned. "Bcc" stands
        for *Blind Carbon Copy*: destinations of the message which are not
        listed in the messages actually sent. So, this field will be empty
        for received messages, but may be present in messages you construct
        yourself.

    $obj->cc()
        Returns the addresses which are specified on the "Cc" header line
        (or lines) A list of [Mail::Address](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AAddress/markdown) objects is returned. "Cc" stands
        for *Carbon Copy*; the people addressed on this line receive the
        message informational, and are usually not expected to reply on its
        content.

    $obj->date()
        Method has been removed for reasons of consistency. Use timestamp()
        or "$msg->head->get('Date')".

    $obj->destinations()
        Returns a list of [Mail::Address](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AAddress/markdown) objects which contains the combined
        info of active "To", "Cc", and "Bcc" addresses. Double addresses are
        removed if detectable.

    $obj->from()
        Returns the addresses from the senders. It is possible to have more
        than one address specified in the "From" field of the message,
        according to the specification. Therefore a list of [Mail::Address](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AAddress/markdown)
        objects is returned, which usually has length 1.

        If you need only one address from a sender, for instance to create a
        "original message by" line in constructed forwarded message body,
        then use sender().

        example: using from() to get all sender addresses

         my @from = $message->from;

    $obj->get($fieldname)
        Returns the value which is stored in the header field with the
        specified name. The $fieldname is case insensitive. The *unfolded
        body* of the field is returned, stripped from any attributes. See
        [Mail::Message::Field::body](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AField%3A%3Abody/markdown)().

        If the field has multiple appearances in the header, only the last
        instance is returned. If you need more complex handing of fields,
        then call [Mail::Message::Head::get](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AHead%3A%3Aget/markdown)() yourself. See study() when you
        want to be smart, doing the better (but slower) job.

        example: the get() short-cut for header fields

         print $msg->get('Content-Type'), "\n";

        Is equivalent to:

         print $msg->head->get('Content-Type')->body, "\n";

    $obj->guessTimestamp()
        Return an estimate on the time this message was sent. The data is
        derived from the header, where it can be derived from the "date" and
        "received" lines. For MBox-like folders you may get the date from
        the from-line as well.

        This method may return "undef" if the header is not parsed or only
        partially known. If you require a time, then use the timestamp()
        method, described below.

        example: using guessTimestamp() to get a transmission date

         print "Receipt ", ($message->timestamp || 'unknown'), "\n";

    $obj->head( [$head] )
        Return (optionally after setting) the $head of this message. The
        head must be an (sub-)class of [Mail::Message::Head](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AHead/markdown). When the head is
        added, status information is taken from it and transformed into
        labels. More labels can be added by the LABELS hash. They are added
        later.

        example:

         my $header = [Mail::Message::Head](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AHead/markdown)->new;
         $msg->head($header);    # set
         my $head = $msg->head;  # get

    $obj->nrLines()
        Returns the number of lines used for the whole message.

    $obj->sender()
        Returns exactly one address, which is the originator of this
        message. The returned [Mail::Address](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AAddress/markdown) object is taken from the
        "Sender" header field, unless that field does not exists, in which
        case the first address from the "From" field is taken. If none of
        both provide an address, "undef" is returned.

        example: using sender() to get exactly one sender address

         my $sender = $message->sender;
         print "Reply to: ", $sender->format, "\n" if defined $sender;

    $obj->study($fieldname)
        Study the content of a field, like get() does, with as main
        difference that a [Mail::Message::Field::Full](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AField%3A%3AFull/markdown) object is returned.
        These objects stringify to an utf8 decoded representation of the
        data contained in the field, where get() does not decode. When the
        field does not exist, then "undef" is returned. See
        [Mail::Message::Field::study](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AField%3A%3Astudy/markdown)().

        example: the study() short-cut for header fields

         print $msg->study('to'), "\n";

        Is equivalent to:

         print $msg->head->study('to'), "\n";       # and
         print $msg->head->get('to')->study, "\n";

        or better: if(my $to = $msg->study('to')) { print "$to\n" } if(my
        $to = $msg->get('to')) { print $to->study, "\n" }

    $obj->subject()
        Returns the message's subject, or the empty string. The subject may
        have encoded characters in it; use study() to get rit of that.

        example: using subject() to get the message's subject

         print $msg->subject;
         print $msg->study('subject');

    $obj->timestamp()
        Get a good timestamp for the message, doesn't matter how much work
        it is. The value returned is compatible with the platform dependent
        result of function time().

        In these days, the timestamp as supplied by the message (in the
        "Date" field) is not trustable at all: many spammers produce illegal
        or unreal dates to influence their location in the displayed folder.

        To start, the received headers are tried for a date (see
        [Mail::Message::Head::Complete::recvstamp](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AHead%3A%3AComplete%3A%3Arecvstamp/markdown)()) and only then the "Date"
        field. In very rare cases, only with some locally produced messages,
        no stamp can be found.

    $obj->to()
        Returns the addresses which are specified on the "To" header line
        (or lines). A list of [Mail::Address](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AAddress/markdown) objects is returned. The people
        addressed here are the targets of the content, and should read it
        contents carefully.

        example: using to() to get all primar destination addresses

         my @to = $message->to;

### The body
    $obj->body( [$body] )
        Return the body of this message. BE WARNED that this returns you an
        object which may be encoded: use decoded() to get a body with usable
        data.

        With options, a new $body is set for this message. This is not for
        normal use unless you understand the consequences: you change the
        message content without changing the message-ID. The right way to go
        is via

         $message = [Mail::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage/markdown)->buildFromBody($body);  # or
         $message = [Mail::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage/markdown)->build($body);          # or
         $message = $origmsg->forward(body => $body);

        The $body must be an (sub-)class of [Mail::Message::Body](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3ABody/markdown). In this
        case, information from the specified body will be copied into the
        header. The body object will be encoded if needed, because messages
        written to file or transmitted shall not contain binary data. The
        converted body is returned.

        When $body is "undef", the current message body will be dissected
        from the message. All relation will be cut. The body is returned,
        and can be connected to a different message.

        example:

         my $body      = $msg->body;
         my @encoded   = $msg->body->lines;

         my $new       = [Mail::Message::Body](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3ABody/markdown)->new(mime_type => 'text/html');
         my $converted = $msg->body($new);

    $obj->contentType()
        Returns the content type header line, or "text/plain" if it is not
        defined. The parameters will be stripped off.

    $obj->decoded(%options)
        Decodes the body of this message, and returns it as a body object.
        Short for "$msg->body->decoded" All %options are passed-on.

    $obj->encode(%options)
        Encode the message to a certain format. Read the details in the
        dedicated manual page [Mail::Message::Body::Encode](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3ABody%3A%3AEncode/markdown). The %options
        which can be specified here are those of the
        [Mail::Message::Body::encode](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3ABody%3A%3Aencode/markdown)() method.

    $obj->isMultipart()
        Check whether this message is a multipart message (has attachments).
        To find this out, we need at least the header of the message; there
        is no need to read the body of the message to detect this.

    $obj->isNested()
        Returns "true" for "message/rfc822" messages and message parts.

    $obj->parts( [<'ALL'|'ACTIVE'|'DELETED'|'RECURSE'|$filter>] )
        Returns the *parts* of this message. Maybe a bit inconvenient: it
        returns the message itself when it is not a multipart.

        Usually, the term *part* is used with *multipart* messages: messages
        which are encapsulated in the body of a message. To abstract this
        concept: this method will return you all header-body combinations
        which are stored within this message except the multipart and
        message/rfc822 wrappers. Objects returned are "[Mail::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage/markdown)"'s and
        [Mail::Message::Part](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3APart/markdown)'s.

        The option default to 'ALL', which will return the message itself
        for single-parts, the nested content of a message/rfc822 object,
        respectively the parts of a multipart without recursion. In case of
        'RECURSE', the parts of multiparts will be collected recursively.
        This option cannot be combined with the other options, which you may
        want: it that case you have to test yourself.

        'ACTIVE' and 'DELETED' check for the deleted flag on messages and
        message parts. The $filter is a code reference, which is called for
        each part of the message; each part as "RECURSE" would return.

        example:

         my @parts = $msg->parts;           # $msg not multipart: returns ($msg)
         my $parts = $msg->parts('ACTIVE'); # returns ($msg)

         $msg->delete;
         my @parts = $msg->parts;           # returns ($msg)
         my $parts = $msg->parts('ACTIVE'); # returns ()

### Flags
    $obj->delete()
        Flag the message to be deleted, which is a shortcut for
        $msg->label(deleted => time); The real deletion only takes place on
        a synchronization of the folder. See deleted() as well.

        The time stamp of the moment of deletion is stored as value, but
        that is not always preserved in the folder (depends on the
        implementation). When the same message is deleted more than once,
        the first time stamp will stay.

        example:

         $message->delete;
         $message->[deleted(1)](https://www.chedong.com/phpMan.php/man/deleted/1/markdown);  # exactly the same
         $message->label(deleted => 1);
         delete $message;

    $obj->deleted( [BOOLEAN] )
        Set the delete flag for this message. Without argument, the method
        returns the same as isDeleted(), which is preferred. When a true
        value is given, delete() is called.

        example:

         $message->[deleted(1)](https://www.chedong.com/phpMan.php/man/deleted/1/markdown);          # delete
         $message->delete;              # delete (preferred)

         $message->[deleted(0)](https://www.chedong.com/phpMan.php/man/deleted/0/markdown);          # undelete

         if($message->deleted) {...}    # check
         if($message->isDeleted) {...}  # check (preferred)

    $obj->isDeleted()
        Short-cut for $msg->label('deleted')

        For some folder types, you will get the time of deletion in return.
        This depends on the implementation.

        example:

         next if $message->isDeleted;

         if(my $when = $message->isDeleted) {
            print scalar localtime $when;
         }

    $obj->isModified()
        Returns whether this message is flagged as being modified.
        Modifications are changes in header lines, when a new body is set to
        the message (dangerous), or when labels change.

    $obj->label($label|PAIRS)
        Return the value of the $label, optionally after setting some
        values. In case of setting values, you specify key-value PAIRS.

        Labels are used to store knowledge about handling of the message
        within the folder. Flags about whether a message was read, replied
        to, or scheduled for deletion.

        Some labels are taken from the header's "Status" and "X-Status"
        lines. Folder types like MH define a separate label file, and
        Maildir adds letters to the message filename. But the MailBox labels
        are always the same.

        example:

         print $message->label('seen');
         if($message->label('seen')) {...};
         $message->label(seen => 1);

         $message->label(deleted => 1);  # same as $message->delete

    $obj->labels()
        Returns all known labels. In SCALAR context, it returns the
        knowledge as reference to a hash. This is a reference to the
        original data, but you shall *not* change that data directly: call
        "label" for changes!

        In LIST context, you get a list of names which are defined. Be
        warned that they will not all evaluate to true, although most of
        them will.

    $obj->labelsToStatus()
        When the labels were changed, that may effect the "Status" and/or
        "X-Status" header lines of mbox messages. Read about the relation
        between these fields and the labels in the DETAILS chapter.

        The method will carefully only affect the result of modified() when
        there is a real change of flags, so not for each call to label().

    $obj->modified( [BOOLEAN] )
        Returns (optionally after setting) whether this message is flagged
        as being modified. See isModified().

    $obj->statusToLabels()
        Update the labels according the status lines in the header. See the
        description in the DETAILS chapter.

### The whole message as text
    $obj->file()
        Inherited, see "The whole message as text" in
        [Mail::Message::Construct::Text](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AConstruct%3A%3AText/markdown)

    $obj->lines()
        Inherited, see "The whole message as text" in
        [Mail::Message::Construct::Text](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AConstruct%3A%3AText/markdown)

    $obj->printStructure( [$fh|undef],[$indent] )
        Inherited, see "The whole message as text" in
        [Mail::Message::Construct::Text](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AConstruct%3A%3AText/markdown)

    $obj->string()
        Inherited, see "The whole message as text" in
        [Mail::Message::Construct::Text](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AConstruct%3A%3AText/markdown)

### Internals
    $obj->clonedFrom()
        Returns the $message which is the source of this message, which was
        created by a clone() operation.

    [Mail::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage/markdown)->coerce($message, %options)
        Coerce a $message into a [Mail::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage/markdown). In some occasions, for
        instance where you add a message to a folder, this coercion is
        automatically called to ensure that the correct message type is
        stored.

        The coerced message is returned on success, otherwise "undef". The
        coerced message may be a reblessed version of the original message
        or a new object. In case the message has to be specialized, for
        instance from a general [Mail::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage/markdown) into a
        [Mail::Box::Mbox::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3ABox%3A%3AMbox%3A%3AMessage/markdown), no copy is needed. However, to coerce a
        [Mail::Internet](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AInternet/markdown) object into a [Mail::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage/markdown), a lot of copying and
        converting will take place.

        Valid MESSAGEs which can be coerced into [Mail::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage/markdown) objects are
        of type

        *   Any type of [Mail::Box::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3ABox%3A%3AMessage/markdown)

        *   [MIME::Entity](https://www.chedong.com/phpMan.php/perldoc/MIME%3A%3AEntity/markdown) objects, using [Mail::Message::Convert::MimeEntity](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AConvert%3A%3AMimeEntity/markdown)

        *   [Mail::Internet](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AInternet/markdown) objects, using
            [Mail::Message::Convert::MailInternet](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AConvert%3A%3AMailInternet/markdown)

        *   [Email::Simple](https://www.chedong.com/phpMan.php/perldoc/Email%3A%3ASimple/markdown) objects, using [Mail::Message::Convert::EmailSimple](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AConvert%3A%3AEmailSimple/markdown)

        *   [Email::Abstract](https://www.chedong.com/phpMan.php/perldoc/Email%3A%3AAbstract/markdown) objects

        [Mail::Message::Part](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3APart/markdown)'s, which are extensions of "[Mail::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage/markdown)"'s,
        can also be coerced directly from a [Mail::Message::Body](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3ABody/markdown).

        example:

         my $folder  = [Mail::Box::Mbox](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3ABox%3A%3AMbox/markdown)->new;
         my $message = [Mail::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage/markdown)->build(...);

         my $coerced = [Mail::Box::Mbox::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3ABox%3A%3AMbox%3A%3AMessage/markdown)->coerce($message);
         $folder->addMessage($coerced);

        Simpler replacement for the previous two lines:

         my $coerced = $folder->addMessage($message);

    $obj->isDelayed()
        Check whether the message is delayed (not yet read from file).
        Returns true or false, dependent on the body type.

    $obj->readBody( $parser, $head, [$bodytype] )
        Read a body of a message. The $parser is the access to the folder's
        file, and the $head is already read. Information from the $head is
        used to create expectations about the message's length, but also to
        determine the mime-type and encodings of the body data.

        The $bodytype determines which kind of body will be made and
        defaults to the value specified by new(body_type). $bodytype may be
        the name of a body class, or a reference to a routine which returns
        the body's class when passed the $head as only argument.

    $obj->readFromParser( $parser, [$bodytype] )
        Read one message from file. The $parser is opened on the file. First
        readHead() is called, and the head is stored in the message. Then
        readBody() is called, to produce a body. Also the body is added to
        the message without decodings being done.

        The optional $bodytype may be a body class or a reference to a code
        which returns a body-class based on the header.

    $obj->readHead( $parser, [$class] )
        Read a head into an object of the specified $class. The $class
        defaults to new(head_type). The $parser is the access to the
        folder's file.

    $obj->recursiveRebuildPart($part, %options)
        Inherited, see "Internals" in [Mail::Message::Construct::Rebuild](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AConstruct%3A%3ARebuild/markdown)

    $obj->storeBody($body)
        Where the body() method can be used to set and get a body, with all
        the necessary checks, this method is bluntly adding the specified
        body to the message. No conversions, not checking.

    $obj->takeMessageId( [STRING] )
        Take the message-id from the STRING, or create one when the "undef"
        is specified. If not STRING nor "undef" is given, the current header
        of the message is requested for the value of the 'Message-ID' field.

        Angles (if present) are removed from the id.

### Error handling
    Extends "Error handling" in [Mail::Reporter](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AReporter/markdown).

    $obj->AUTOLOAD()
        Inherited, see "METHODS" in [Mail::Message::Construct](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AConstruct/markdown)

    $obj->addReport($object)
        Inherited, see "Error handling" in [Mail::Reporter](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AReporter/markdown)

    $obj->defaultTrace( [$level]|[$loglevel, $tracelevel]|[$level,
    $callback] )
    [Mail::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage/markdown)->defaultTrace( [$level]|[$loglevel, $tracelevel]|[$level,
    $callback] )
        Inherited, see "Error handling" in [Mail::Reporter](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AReporter/markdown)

    $obj->errors()
        Inherited, see "Error handling" in [Mail::Reporter](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AReporter/markdown)

    $obj->log( [$level, [$strings]] )
    [Mail::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage/markdown)->log( [$level, [$strings]] )
        Inherited, see "Error handling" in [Mail::Reporter](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AReporter/markdown)

    $obj->logPriority($level)
    [Mail::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage/markdown)->logPriority($level)
        Inherited, see "Error handling" in [Mail::Reporter](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AReporter/markdown)

    $obj->logSettings()
        Inherited, see "Error handling" in [Mail::Reporter](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AReporter/markdown)

    $obj->notImplemented()
        Inherited, see "Error handling" in [Mail::Reporter](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AReporter/markdown)

    $obj->report( [$level] )
        Inherited, see "Error handling" in [Mail::Reporter](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AReporter/markdown)

    $obj->reportAll( [$level] )
        Inherited, see "Error handling" in [Mail::Reporter](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AReporter/markdown)

    $obj->shortSize( [$value] )
    [Mail::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage/markdown)->shortSize( [$value] )
        Represent an integer $value representing the size of file or memory,
        (which can be large) into a short string using M and K (Megabytes
        and Kilobytes). Without $value, the size of the message head is
        used.

    $obj->shortString()
        Convert the message header to a short string (without trailing
        newline), representing the most important facts (for debugging
        purposes only). For now, it only reports size and subject.

    $obj->trace( [$level] )
        Inherited, see "Error handling" in [Mail::Reporter](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AReporter/markdown)

    $obj->warnings()
        Inherited, see "Error handling" in [Mail::Reporter](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AReporter/markdown)

### Cleanup
    Extends "Cleanup" in [Mail::Reporter](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AReporter/markdown).

    $obj->DESTROY()
        Inherited, see "Cleanup" in [Mail::Reporter](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AReporter/markdown)

    $obj->destruct()
        Remove the information contained in the message object. This will be
        ignored when more than one reference to the same message object
        exists, because the method has the same effect as assigning "undef"
        to the variable which contains the reference. Normal garbage
        collection will call "DESTROY()" when possible.

        This method is only provided to hide differences with messages which
        are located in folders: their [Mail::Box::Message::destruct](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3ABox%3A%3AMessage%3A%3Adestruct/markdown)() works
        quite differently.

        example: of [Mail::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage/markdown) destruct

         my $msg = [Mail::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage/markdown)->read;
         $msg->destruct;
         $msg = undef;    # same

## DETAILS
### Structure of a Message
    A MIME-compliant message is build upon two parts: the *header* and the
    *body*.

   The header
    The header is a list of fields, some spanning more than one line
    (*folded*) each telling something about the message. Information stored
    in here are for instance the sender of the message, the receivers of the
    message, when it was transported, how it was transported, etc. Headers
    can grow quite large.

    In MailBox, each message object manages exactly one header object (a
    [Mail::Message::Head](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AHead/markdown)) and one body object (a [Mail::Message::Body](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3ABody/markdown)). The
    header contains a list of header fields, which are represented by
    [Mail::Message::Field](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AField/markdown) objects.

   The body
    The body contains the "payload": the data to be transferred. The data
    can be encoded, only accessible with a specific application, and may use
    some weird character-set, like Vietnamese; the MailBox distribution
    tries to assist you with handling these e-mails without the need to know
    all the details. This additional information ("meta-information") about
    the body data is stored in the header. The header contains more
    information, for instance about the message transport and relations to
    other messages.

### Message object implementation
    The general idea about the structure of a message is

     [Mail::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage/markdown)
      |  |
      |  `-has-one--[Mail::Message::Body](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3ABody/markdown)
      |
      `----has-one--[Mail::Message::Head](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AHead/markdown)
                      |
                      `-has-many--[Mail::Message::Field](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AField/markdown)

    However: there are about 7 kinds of body objects, 3 kinds of headers and
    3 kinds of fields. You will usually not see too much of these kinds,
    because they are merely created for performance reasons and can be used
    all the same, with the exception of the multipart bodies.

    A multipart body is either a [Mail::Message::Body::Multipart](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3ABody%3A%3AMultipart/markdown) (mime type
    "multipart/*") or a [Mail::Message::Body::Nested](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3ABody%3A%3ANested/markdown) (mime type
    "message/rfc822"). These bodies are more complex:

     [Mail::Message::Body::Multipart](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3ABody%3A%3AMultipart/markdown)
      |
      `-has-many--[Mail::Message::Part](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3APart/markdown)
                   |  |
                   |  `-has-one--[Mail::Message::Body](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3ABody/markdown)
                   |
                   `----has-one--[Mail::Message::Head](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AHead/markdown)

    Before you try to reconstruct multiparts or nested messages yourself,
    you can better take a look at [Mail::Message::Construct::Rebuild](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3AConstruct%3A%3ARebuild/markdown).

### Message class implementation
    The class structure of messages is very close to that of folders. For
    instance, a [Mail::Box::File::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3ABox%3A%3AFile%3A%3AMessage/markdown) relates to a [Mail::Box::File](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3ABox%3A%3AFile/markdown)
    folder.

    As extra level of inheritance, it has a [Mail::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage/markdown), which is a
    message without location. And there is a special case of message:
    [Mail::Message::Part](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3APart/markdown) is a message encapsulated in a multipart body.

    The message types are:

     [Mail::Box::Mbox::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3ABox%3A%3AMbox%3A%3AMessage/markdown)            [Mail::Box::POP3::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3ABox%3A%3APOP3%3A%3AMessage/markdown)
     |  [Mail::Box::Dbx::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3ABox%3A%3ADbx%3A%3AMessage/markdown)      [Mail::Box::IMAP4::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3ABox%3A%3AIMAP4%3A%3AMessage/markdown)  |
     |  |                                                    |  |
     [Mail::Box::File::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3ABox%3A%3AFile%3A%3AMessage/markdown)             [Mail::Box::Net::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3ABox%3A%3ANet%3A%3AMessage/markdown)
             |                                      |
             |       [Mail::Box::Maildir::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3ABox%3A%3AMaildir%3A%3AMessage/markdown)    |
             |       |   [Mail::Box::MH::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3ABox%3A%3AMH%3A%3AMessage/markdown)     |
             |       |   |                          |
             |       [Mail::Box::Dir::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3ABox%3A%3ADir%3A%3AMessage/markdown)        |
             |                |                     |
             `------------.   |   .-----------------'
                          |   |   |
                       [Mail::Box::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3ABox%3A%3AMessage/markdown)    [Mail::Message::Part](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3APart/markdown)
                              |                     |
                              |       .-------------'
                              |       |
                          [Mail::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage/markdown)
                              |
                              |
                        [Mail::Reporter](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AReporter/markdown) (general base class)

    By far most folder features are implemented in [Mail::Box](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3ABox/markdown), so available
    to all folder types. Sometimes, features which appear in only some of
    the folder types are simulated for folders that miss them, like
    sub-folder support for MBOX.

    Two strange other message types are defined: the [Mail::Message::Dummy](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage%3A%3ADummy/markdown),
    which fills holes in [Mail::Box::Thread::Node](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3ABox%3A%3AThread%3A%3ANode/markdown) lists, and a
    [Mail::Box::Message::Destructed](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3ABox%3A%3AMessage%3A%3ADestructed/markdown), this is an on purpose demolished message
    to reduce memory consumption.

### Labels
    Labels (also named "Flags") are used to indicate some special condition
    on the message, primary targeted on organizational issues: which
    messages are already read or should be deleted. There is a very strong
    user relation to labels.

    The main complication is that each folder type has its own way of
    storing labels. To give an indication: MBOX folders use "Status" and
    "X-Status" header fields, MH uses a ".mh-sequences" file, MAILDIR
    encodes the flags in the message's filename, and IMAP has flags as part
    of the protocol.

    Besides, some folder types can store labels with user defined names,
    where other lack that feature. Some folders have case-insensitive
    labels, other don't. Read all about the specifics in the manual page of
    the message type you actually have.

   Predefined labels
    To standardize the folder types, MailBox has defined the following
    labels, which can be used with the label() and labels() methods on all
    kinds of messages:

    *   deleted

        This message is flagged to be deleted once the folder closes. Be
        very careful about the concept of 'delete' in a folder context : it
        is only a flag, and does not involve immediate action! This means,
        for instance, that the memory which is used by Perl to store the
        message is not released immediately (see destruct() if you need to).

        The methods delete(), deleted(), and isDeleted() are only short-cuts
        for managing the "delete" label (as of MailBox 2.052).

    *   draft

        The user has prepared this message, but is has not been send (yet).
        This flag is not automatically added to a message by MailBox, and
        has only a meaning in user applications.

    *   flagged

        Messages can be *flagged* for some purpose, for instance as result
        of a search for spam in a folder. The [Mail::Box::messages](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3ABox%3A%3Amessages/markdown)() method
        can be used to collect all these flagged messages from the folder.

        Probably it is more useful to use an understandable name (like
        "spam") for these selections, however these self-defined labels can
        not stored in all folder types.

    *   old

        The message was already in the folder when it was opened the last
        time, so was not recently added to the folder. This flag will never
        automatically be set by MailBox, because it would probably conflict
        with the user's idea of what is old.

    *   passed

        Not often used or kept, this flag indicates that the message was
        bounced or forwarded to someone else.

    *   replied

        The user (or application) has sent a message back to the sender of
        the message, as response of this one. This flag is automatically set
        if you use reply(), but not with forward() or bounce().

    *   seen

        When this flag is set, the receiver of the message has consumed the
        message. A mail user agent (MUA) will set this flag when the user
        has opened the message once.

   Status and X-Status fields
    Mbox folders have no special means of storing information about messages
    (except the message separator line), and therefore have to revert to
    adding fields to the message header when something special comes up.
    This feature is also enabled for POP3, although whether that works
    depends on the POP server.

    All applications which can handle mbox folders support the "Status" and
    "X-Status" field convensions. The following encoding is used:

     Flag   Field       Label
     R      Status   => seen    (Read)
     O      Status   => old     (not recent)
     A      X-Status => replied (Answered)
     F      X-Status => flagged

    There is no special flag for "deleted", which most other folders
    support: messages flagged to be deleted will never be written to a
    folder file when it is closed.

## DIAGNOSTICS
    Error: Cannot coerce a $class object into a $class object
    Error: Cannot include forward source as $include.
        Unknown alternative for the forward(include). Valid choices are
        "NO", "INLINE", "ATTACH", and "ENCAPSULATE".

    Error: Cannot include reply source as $include.
        Unknown alternative for the "include" option of reply(). Valid
        choices are "NO", "INLINE", and "ATTACH".

    Error: Method bounce requires To, Cc, or Bcc
        The message bounce() method forwards a received message off to
        someone else without modification; you must specified it's new
        destination. If you have the urge not to specify any destination,
        you probably are looking for reply(). When you wish to modify the
        content, use forward().

    Error: Method forwardAttach requires a preamble
    Error: Method forwardEncapsulate requires a preamble
    Error: No address to create forwarded to.
        If a forward message is created, a destination address must be
        specified.

    Error: No default mailer found to send message.
        The message send() mechanism had not enough information to
        automatically find a mail transfer agent to sent this message.
        Specify a mailer explicitly using the "via" options.

    Error: No rebuild rule $name defined.
    Error: Only build() [Mail::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage/markdown)'s; they are not in a folder yet
        You may wish to construct a message to be stored in a some kind of
        folder, but you need to do that in two steps. First, create a normal
        [Mail::Message](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3AMessage/markdown), and then add it to the folder. During this
        [Mail::Box::addMessage](https://www.chedong.com/phpMan.php/perldoc/Mail%3A%3ABox%3A%3AaddMessage/markdown)() process, the message will get coerce()-d
        into the right message type, adding storage information and the
        like.

    Error: Package $package does not implement $method.
        Fatal error: the specific package (or one of its superclasses) does
        not implement this method where it should. This message means that
        some other related classes do implement this method however the
        class at hand does not. Probably you should investigate this and
        probably inform the author of the package.

    Error: coercion starts with some object

## SEE ALSO
    This module is part of Mail-Message distribution version 3.012, built on
    February 11, 2022. Website: <http://perl.overmeer.net/CPAN/>

## LICENSE
    Copyrights 2001-2022 by [Mark Overmeer <<markov@cpan.org>>]. For other
    contributors see ChangeLog.

    This program is free software; you can redistribute it and/or modify it
    under the same terms as Perl itself. See <http://dev.perl.org/licenses/>

