SYNOPSIS

       in .qmail: |srsreverse

DESCRIPTION

       Upon reception by qmail-smtpd, qmail-local may feed a locally delivered
       bounce email through srsrevers in order to reconstruct the original
       sender from the received SRS address provided in the local part and to
       forward the bounce mail to its original address.

SRS DOMAINS

       In order to accept emails for SRS modified return addresses, you need
       to setup those in rcpthosts.  If your domain is example.com in
       rcpthosts you probably want to set up additionally srs.example.com.
       However, .example.com would be fine as well.

VIRTUAL SRS USER

       SRS can facilitate a virtual user typically named srs and thus requires
       an entry like srs.example.com:srs in virtualdomains.

DOT QMAIL

       srsreverse is called from a dot-qmail file which could be
       SQMAIL/alias/.qmail-srs-default.

CONTROL FILES

       srsreverse reads the control file virtualdomains to exfiltrate the
       (virtual) SRS user name for the received domain, if given. With the
       evaluated srsdomain, srsrevers fetches the SRS secret from srsdomains
       in order to validate the SRS bounce address.

ENVIRONMENT VARIABLES

       srsrverse reads the environment variables DTLINE, HOST, and RECIPIENTS.
       HOST is used to determine the srsdomain.  The forwarding bounce address
       is reconstructed from the local part of RECIPIENTS.

VERP

       The Sender Rewriting Scheme SRS can be considered as tailored form of
       VERP: Variable Envelope Return Path.  The chosen primary delimiter = is
       recognized by qmail-smtpd's recipient extension.

REFERENCE

       srsreverse uses srs2.c from libsrs2.

SEE ALSO

       srsforward(1), dot-qmail(5), qmail-command(8), qmail-queue(8), qmail-
       send(8).



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