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       formail - mail (re)formatter


       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


       formail 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  all
       bogus `From ' lines with a `>'.


       -v   Formail will print its version number and exit.

       -b   Don't  escape any bogus mailbox headers (i.e., lines starting with
            `From ').

       -p prefix
            Define a different quotation prefix.  If unspecified  it  defaults
            to `>'.

       -Y   Assume  traditional Berkeley mailbox format, ignoring any Content-
            Length: fields.

       -c   Concatenate continued fields in the header.  Might  be  convenient
            when  postprocessing  mail  with  standard  (line  oriented)  text

       -z   Ensure a whitespace exists between field name  and  content.   Zap
            fields  which  contain  only  a  single whitespace character.  Zap
            leading and trailing whitespace on fields extracted with -x.

       -f   Force formail to simply pass along any non-mailbox  format  (i.e.,
            don't generate a `From ' line as the first line).

       -r   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 -i option.
            If you use this option in conjunction with -k, you can prevent the
            body from being `escaped' by also specifying -b.

       -k   When  generating  the auto-reply header or when extracting fields,
            keep the body as well.

       -t   Trust the sender to have  used  a  valid  return  address  in  his
            header.   This  causes formail 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   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).  -s 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 split mails on stdout
            again.  See FILENO.

       -n [maxprocs]
            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   Do  not  require  empty  lines to be preceding the header of a new
            message (i.e.,  the messages could start on every line).

       -d   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 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   Makes formail assume that it is splitting up a BABYL rmail file.

       -m minfields
            Allows you to  specify  the  number  of  consecutive  headerfields
            formail  needs  to  find before it decides it found the start of a
            new message, it defaults to 2.

       -q   Tells formail to (still detect but) be quiet about  write  errors,
            duplicate  messages  and  mismatched Content-Length: fields.  This
            option is on by default, to make it display the messages use  -q-.

       -D maxlen idcache
            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 headerfield
            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 headerfield
            Same as -x, but also preserves/includes the field name.

       -a headerfield
            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 headerfield
            Append a custom headerfield onto the header in any case.

       -i headerfield
            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 headerfield
            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 headerfield
            Make  the  first  occurrence of this field unique, and thus delete
            all subsequent occurrences of it.

       -U headerfield
            Make the last occurrence of this field unique, and thus delete all
            preceding occurrences of it.

       -R oldfield newfield
            Renames all occurrences of the fieldname oldfield into newfield.

            Skip the first skip messages while splitting.

            Output at most total messages while splitting.


       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 regarding 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
       headers  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 established 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.


            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
              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 ""
              sed -e '/^$/ q'

       To extract the body from a message:
              formail -I ""
              sed -e '1,/^$/ d'


       mail(1), sendmail(8), procmail(1), sed(1), sh(1), RFC822, RFC2822,


       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

       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.


       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.

       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_:'.


       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 closes its
       output or terminates itself.

       If formail is instructed to generate an autoreply mail, it  will  never
       put more than one address in the `To:' field.


       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

       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 (except 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  into
       normal RFC822 continuations.


       Calling up formail with the -h or -? options will cause it to display a
       command-line help page.


       This program is part of the  procmail  mail-processing-package  (v3.22)
       available    at   or   in


       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 subscription request to
       (this is a readonly list).


       Stephen R. van den Berg
       Philip A. Guenther