formail - mail (re)formatter
...]]] is a filter that can be used to force mail into mailbox format, perform `From ' escaping, 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 bogus `From ' lines with a `>'. Don't escape any bogus mailbox headers (i.e. lines starting with `From '). Define a different quotation prefix. If unspecified it defaults to `>'. Assume traditional Berkeley mailbox format, ignoring any fields. Concatenate continued fields in the header. Might be convenient when postprocessing mail with standard (line oriented) text utilities. Ensure a space exists between field name and content. Zap fields which contain only a space. Zap leading and trailing whitespace on fields extracted with Force formail to simply pass along any non-mailbox format (i.e. don't generate a `From ' line as the first line). Generate an auto-reply header. This will normally throw away all the existing fields (except X-Loop:) in the original message, fields you wish to preserve need to be named using the option. If you use this option in conjunction with you can prevent the body from being `escaped' by also specifying When generating the auto-reply header or when extracting fields, keep the body as well. Trust the sender to have used a valid return address in his header. This option will be most useful when generating auto-reply headers from news articles. If this option is not turned on, formail tends to favour machine-generated addresses in the header. The input will be split up into separate mail messages, and piped into a program one by one (a new program is started for every part). has to be the last option specified, the first argument following it is expected to be the name of a program, any other arguments will be passed along to it. If you omit the program, then formail will simply concatenate the splitted mails on stdout again. See Tell formail not to wait for every program to finish before starting the next (causes splits to be processed in parallel). Do not require empty lines to be preceding the header of a new message (i.e. the messages could start on every line). Tell formail that the messages it is supposed to split need not be in strict mailbox format (i.e. allows you to split digests/articles or non-standard mailbox formats). This disables recognition of the field. Makes formail assume that it is splitting up a BABYL rmail file. Allows you to specify the number of consecutive fields formail needs to find before it decides it found the start of a new message, it defaults to 2. Tells formail to (still detect but) be quiet about write errors, duplicate messages and mismatched fields. This option is on by default, to make it display the messages use Formail will detect if the Message-ID of the current message has already been seen using an file of approximately 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 formail will look at the of the sender at the Message-ID. Extract the contents of this from the header, display it as a single line. Same as but also preserves the field name. Append a custom onto the header; but only if a similar field does not exist yet. If you specify either one of the field names or with no field contents, then formail will generate a unique message-ID for you. Append a custom onto the header in any case. Same as except that any existing similar fields are renamed by prepending an ``Old-'' prefix. If consists only of a field-name, it will not be appended. Same as except that any existing similar fields are simply removed. If consists only of a field-name, it effectively deletes the field. Make the first occurrence of this field unique, and thus delete all subsequent occurrences of it. Make the last occurrence of this field unique, and thus delete all preceding occurrences of it. Renames all occurrences of the fieldname into Skip the first messages while splitting. Output at most messages while splitting. While splitting, formail assigns the message number currently being output to this variable. 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. 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 <old_mailbox >>new_mailbox Or, if you have a very tolerant mailer: formail -a Date: -ds <old_mailbox >>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' 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 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 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. You can save yourself and others a lot of grief if you try to avoid using this autoreply feature 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. 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 differ from that expected by most mail readers. If formail is instructed to delete or rename the leading `From ' line, it will not automatically 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 terminates itself. Formail is eight-bit clean. When formail has to determine the sender's address, every RFC 822 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 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 (except when splitting digests or Berkeley mailbox format is assumed). 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 (v3.10 1994/10/31) available at your nearest USENET comp.sources.misc archive, or at ftp.informatik.rwth-aachen.de as

MAILINGLIST
There exists a mailinglist for questions relating to any program in the procmail package: procmail@informatik.rwth-aachen.de for submitting questions/answers. procmail-request@informatik.rwth-aachen.de for subscription requests.

AUTHOR
Stephen R. van den Berg at RWTH-Aachen, Germany berg@pool.informatik.rwth-aachen.de