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qmail-qfilter(1)       DragonFly General Commands Manual      qmail-qfilter(1)

NAME
       qmail-qfilter - front end for qmail-queue that does filtering

SYNOPSIS
       qmail-qfilter filter [ -- filter ...  ]

DESCRIPTION
       qmail-qfilter sends the message text through each of the filter
       commands named on the command line.  Each filter is run seperately,
       with standard input opened to the input email, and standard output
       opened to a new temporary file that will become the input to either the
       next filter, or qmail-queue.  If the filter does not modify the message
       it passes unchanged to the next step.  It also makes the envelope
       avaliable to each filter as file descriptor 3.  File descriptor 4 is
       opened to a new temporary file for the modified envelope, allowing the
       filter to modify the envelope or the message.  If the filter does not
       modify the envelope, the envelope remains unchanged for either the next
       filter or qmail-queue.  This provides compatibility for existing
       filters that do not know about the envelope.  qmail-qfilter also opens
       up file descriptor 5 to a temporary file.  If this file is empty after
       all the filters have executed, its contents are read and used to
       specify a program to execute in place of qmail-queue.  Each filter on
       the command line in seperated with --.

RETURN VALUES
       Returns 51 (out of memory), 53 (write error), or 81 (internal error) if
       it can't create the temporary files or has problems executing the
       filters.  Returns 91 (bad envelope data) if it can't read or parse the
       envelope data.  If a filter returns anything other than 0 or 99,
       qmail-qfilter returns its exit code.  If a filter returns 99,
       qmail-qfilter returns 0 immediately without running any other filters.
       Otherwise returns the exit code of qmail-queue.

ENVIRONMENT
       For cmpatibility with previous versions, qmail-qfilter sets QMAILUSER
       and QMAILHOST to the user and host portions of the envelope sender
       address, and unsets QMAILNAME.  It also sets QMAILRCPTS to the list of
       envelope recipients, each followed by a newline.

       It also sets ENVSIZE to the size of the envelope, MSGSIZE to the length
       of the message, and NUMRCPTS to the number of recipients. These values
       are updated before each filter is run.

       If QQF_QMAILQUEUE is set, its value is used in place of qmail-queue.

SEE ALSO
       qmail-queue(8)

NOTES
       $QMAILQUEUE is deliberately not used to override qmail-queue in order
       to avoid recursive loops with configurations that set $QMAILQUEUE to
       invoke qmail-qfilter itself.

WARNINGS
       If you are using qmail-inject -n as one of the filters, you may want to
       unset MAILUSER, USER, and LOGNAME by using env -u QMAILNAME -u MAILNAME
       -u NAME qmail-inject -n as the command to invoke qmail-inject.  Note
       that some the env command with some OS's doesn't support the -u option.

       A message with an excessive number of recipients (more than 64K bytes
       of recipient data on Linux) will cause execution of the filter programs
       to fail, and for the message to be rejected.

       The same temporary file is reused for file descriptor 5 for each
       filter.  Make sure each filter writes a trailing ASCII NUL byte
       following the program name, as multiple filters could otherwise
       overwrite the value in undesireable ways.

                                                              qmail-qfilter(1)