# phpman > man > formail(1) *Source: tldr-pages* --- [FORMAIL(1)](https://www.chedong.com/phpMan.php/man/FORMAIL/1/markdown) General Commands Manual [FORMAIL(1)](https://www.chedong.com/phpMan.php/man/FORMAIL/1/markdown) ## NAME formail - mail (re)formatter ## SYNOPSIS **formail** [**+**_skip_] [**-**_total_] [**-bczfrktedqBY**] [**-p** _prefix_] [**-D** _maxlen_ _idcache_] [**-l** _folder_] [**-x** _headerfield_] [**-X** _headerfield_] [**-a** _headerfield_] [**-A** _headerfield_] [**-i** _headerfield_] [**-I** _headerfield_] [**-u** _headerfield_] [**-U** _headerfield_] [**-R** _oldfield_ _newfield_] [**-n** [_maxprocs_ ]] [**-m** _minfields_] [**-s** [_command_ [_arg_ ...]]] ### formail -v ## DESCRIPTION **formail** is a filter that can be used to force mail into mailbox format, perform `From ' es‐ caping, generate auto-replying headers, do simple header munging/extracting or split up a mailbox/digest/articles file. The mail/mailbox/article contents will be expected on stdin. If formail is supposed to determine the sender of the mail, but is unable to find any, it will substitute `foo@bar'. If formail is started without any command line options, it will force any mail coming from stdin into mailbox format and will escape **all** bogus `From ' lines with a `>'. ## OPTIONS ### -v ### -b ### -p Define a different quotation prefix. If unspecified it defaults to `>'. ### -Y ### -c mail with standard (line oriented) text utilities. ### -z only a single whitespace character. Zap leading and trailing whitespace on fields ex‐ tracted with **-x**. ### -f ' line as the first line). ### -r (except X-Loop:) in the original message, fields you wish to preserve need to be named using the **-i** option. If you use this option in conjunction with **-k**, you can prevent the body from being `escaped' by also specifying **-b**. ### -k ### -t to select the _header_ _sender_ instead of the _envelope_ _sender_ for the reply. This option should be used when generating auto-reply headers from news articles or when the sender of the message is expecting a reply. ### -s one (a new program is started for every part). **-s** has to be the last option specified, the first argument following it is expected to be the name of a program, any other argu‐ ments will be passed along to it. If you omit the program, then formail will simply concatenate the split mails on stdout again. See **FILENO**. ### -n Tell formail not to wait for every program to finish before starting the next (causes splits to be processed in parallel). _Maxprocs_ optionally specifies an upper limit on the number of concurrently running processes. ### -e sages could start on every line). ### -d format (i.e., allows you to split digests/articles or non-standard mailbox formats). This disables recognition of the **Content-Length:** field. ### -l folder Generate a log summary in the same style as procmail. This includes the entire "From " line, the Subject: header field, the folder, and the size of the message in bytes. The mailstat command can be used to summarize logs in this format. ### -B ### -m Allows you to specify the number of consecutive headerfields formail needs to find be‐ fore it decides it found the start of a new message, it defaults to 2. ### -q mismatched **Content-Length:** fields. This option is on by default, to make it display the messages use **-q-**. ### -D Formail will detect if the Message-ID of the current message has already been seen using an _idcache_ file of approximately _maxlen_ size. If not splitting, it will return success if a duplicate has been found. If splitting, it will not output duplicate messages. If used in conjunction with **-r**, formail will look at the _mail_ _address_ of the envelope sender _instead_ at the Message-ID. ### -x Extract the contents of this _headerfield_ from the header. Line continuations will be left intact; if you want the value on a single line then you'll also need the **-c** option. ### -X Same as **-x**, but also preserves/includes the field name. ### -a Append a custom _headerfield_ onto the header; but only if a similar field does not exist yet. If you specify either one of the field names **Message-ID:** or **Resent-Message-ID:** with no field contents, then formail will generate a unique message-ID for you. ### -A Append a custom _headerfield_ onto the header in any case. ### -i Same as **-A**, except that any existing similar fields are renamed by prepending an ``Old-'' prefix. If _headerfield_ consists only of a field-name, it will not be appended. ### -I Same as **-i**, except that any existing similar fields are simply removed. If _headerfield_ consists only of a field-name, it effectively deletes the field. ### -u Make the first occurrence of this field unique, and thus delete all subsequent occur‐ rences of it. ### -U Make the last occurrence of this field unique, and thus delete all preceding occurrences of it. ### -R Renames all occurrences of the fieldname _oldfield_ into _newfield_. **+**_skip_ Skip the first _skip_ messages while splitting. **-**_total_ Output at most _total_ messages while splitting. ## NOTES When renaming, removing, or extracting fields, partial fieldnames may be used to specify all fields that start with the specified value. By default, when generating an auto-reply header procmail selects the envelope sender from the input message. This is correct for vacation messages and other automatic replies regard‐ ing the routing or delivery of the original message. If the sender is expecting a reply or the reply is being generated in response to the contents of the original message then the -t option should be used. **RFC822**, the original standard governing the format of Internet mail messages, did not specify whether Resent header fields (those that begin with `Resent-', such as `Resent-From:') should be considered when generating a reply. Since then, the recommended usage of the Resent head‐ ers has evolved to consider them as purely informational and not for use when generating a reply. This has been codified in **RFC2822**, the new Internet Message Format standard, which states in part: Resent fields are used to identify a message as having been reintroduced into the transport system by a user. The purpose of using resent fields is to have the message appear to the final recipient as if it were sent directly by the original sender, with all of the original fields remaining the same....They MUST NOT be used in the normal processing of replies or other such automatic actions on messages. While formail now ignores Resent headers when generating header replies, versions of formail prior to 3.14 gave such headers a high precedence. If the old behavior is needed for estab‐ lished applications it can be specified by calling formail with the option `-a Resent-' in addition to the -r and -t options. This usage is deprecated and should not be used in new applications. ## ENVIRONMENT **FILENO** While splitting, formail assigns the message number currently being output to this vari‐ able. By presetting FILENO, you can change the initial message number being used and the width of the zero-padded output. If FILENO is unset it will default to 000. If FILENO is non-empty and does not contain a number, FILENO generation is disabled. ## EXAMPLES To split up a digest one usually uses: formail +1 -ds >>the_mailbox_of_your_choice or formail +1 -ds procmail To remove all Received: fields from the header: formail -I Received: To remove all fields except From: and Subject: from the header: formail -k -X From: -X Subject: To supersede the Reply-To: field in a header you could use: formail -i "Reply-To: foo@bar" To convert a non-standard mailbox file into a standard mailbox file you can use: formail -ds >new_mailbox Or, if you have a very tolerant mailer: formail -a Date: -ds >new_mailbox To extract the header from a message: formail -X "" or sed -e '/^$/ q' To extract the body from a message: formail -I "" or sed -e '1,/^$/ d' ## SEE ALSO [**mail**(1)](https://www.chedong.com/phpMan.php/man/mail/1/markdown), [**sendmail**(8)](https://www.chedong.com/phpMan.php/man/sendmail/8/markdown), [**procmail**(1)](https://www.chedong.com/phpMan.php/man/procmail/1/markdown), [**sed**(1)](https://www.chedong.com/phpMan.php/man/sed/1/markdown), [**sh**(1)](https://www.chedong.com/phpMan.php/man/sh/1/markdown), **RFC822**, **RFC2822**, **RFC1123** ## DIAGNOSTICS Can't fork Too many processes on this machine. Content-Length: field exceeds actual length by nnn bytes The Content-Length: field in the header specified a length that was longer than the actual body. This causes this message to absorb a number of subsequent messages following it in the same mailbox. Couldn't write to stdout The program that formail was trying to pipe into didn't accept all the data formail sent to it; this diagnostic can be suppressed by the **-q** option. Duplicate key found: x The Message-ID or sender x in this message was found in the idcache; this diagnostic can be suppressed by the **-q** option. Failed to execute "x" Program not in path, or not executable. File table full Too many open files on this machine. Invalid field-name: "x" The specified field-name "x" contains control characters, or cannot be a partial field-name for this option. ## WARNINGS You can save yourself and others a lot of grief if you try to avoid using this autoreply fea‐ ture on mails coming through mailinglists. Depending on the format of the incoming mail (which in turn depends on both the original sender's mail agent and the mailinglist setup) formail could decide to generate an autoreply header that replies to the list. In the tradition of UN*X utilities, formail will do exactly what you ask it to, even if it results in a non-**RFC822** compliant message. In particular, formail will let you generate header fields whose name ends in a space instead of a colon. While this is correct for the leading `From ' line, that line is not a header field so much as the message separator for the mbox mailbox format. Multiple occurrences of such a line or any other colonless header field will be considered by many mail programs, including formail itself, as the beginning of a new message. Others will consider the message to be corrupt. Because of this, you should not use the **-i** option with the `From ' line as the resulting renamed line, `Old-From ', will probably not do what you want it to. If you want to save the original `From ' line, rename it with the **-R** option to a legal header field such as `X-From_:'. ## BUGS When formail has to generate a leading `From ' line it normally will contain the current date. If formail is given the option `-a Date:', it will use the date from the `Date:' field in the header (if present). However, since formail copies it verbatim, the format will dif‐ fer from that expected by most mail readers. If formail is instructed to delete or rename the leading `From ' line, it will not automati‐ cally regenerate it as usual. To force formail to regenerate it in this case, include **-a** **'From** **'**. If formail is not called as the first program in a pipe and it is told to split up the input in several messages, then formail will not terminate until the program it receives the input from closes its output or terminates itself. If formail is instructed to generate an autoreply mail, it will **never** put more than one ad‐ dress in the `To:' field. ## MISCELLANEOUS Formail is eight-bit clean. When formail has to determine the sender's address, every **RFC822** conforming mail address is allowed. Formail will always strip down the address to its minimal form (deleting excessive comments and whitespace). The regular expression that is used to find `real' postmarks is: "\n\nFrom [\t ]*[^\t\n ]+[\t ]+[^\n\t ]" If a **Content-Length:** field is found in a header, formail will copy the number of specified bytes in the body verbatim before resuming the regular scanning for message boundaries (ex‐ cept when splitting digests or Berkeley mailbox format is assumed). Any header lines immediately following the leading `From ' line that start with `>From ' are considered to be a continuation of the `From ' line. If instructed to rename the `From ' line, formail will change each leading `>' into a space, thereby transforming those lines in‐ to normal **RFC822** continuations. ## NOTES Calling up formail with the -h or -? options will cause it to display a command-line help page. ## SOURCE This program is part of the _procmail_ _mail-processing-package_ (v3.23pre) available at or ftp.procmail.org in **pub/procmail/**. ## MAILINGLIST There exists a mailinglist for questions relating to any program in the procmail package: <> for submitting questions/answers. <> for subscription requests. If you would like to stay informed about new versions and official patches send a subscrip‐ tion request to (this is a readonly list). ## AUTHORS Stephen R. van den Berg <> Philip A. Guenther <> BuGless 2001/08/04 [FORMAIL(1)](https://www.chedong.com/phpMan.php/man/FORMAIL/1/markdown)