SUMMARY: Unusual Sendmail Alias

From: Art Schoenstadt (
Date: Wed Apr 22 1998 - 15:37:06 CDT

    The basic issue delt with the inability of our mailer (sendmail 8.8.6,
running on a solaris platform) to handle incoming mail with an address of
the form:
where username is a valid user it's being sent to! We wanted to "trap"
enough information to identify the actual sender, and notify him/her of
the problem.

    I got a number of very helpful responses - thanks to all - which
fell into the following general categories:

       (1) Turn on logging (syslog) at a high enough level to capture
            the complete transaction data, which would identify the
            distant sender and host, e.g.

          | Apr 20 20:58:42 penthesilea sendmail[18976]: UAA18976:
          | <>... AntiSpam Setup - No free Relaying
          | Apr 20 20:58:42 penthesilea sendmail[18976]:
          | Ruleset check_rcpt (<>) rejection:
          | 571 <>... AntiSpam Setup - No free Relaying
          | Apr 20 20:58:42 penthesilea sendmail[18976]: UAA18976:
          | from=<>, size=769, class=0, pri=0,
          | nrcpts=0, proto=ESMTP, [136.199.4711]

            This was the easiest "fix," and what we did. In about 20 minutes
            we got the "trap" we needed. (Because our host is a campus
            mailhub for over 3,000 users, we didn't have that level of logging
            turned on.)

       (2) Rewrite some of the rules in to delete the
            portion of the address, e.g. near the top of S3 include one
            of the following rewrites:
                R$*mailto:$* $1$2 Drop mailto entirely

            We'll likely experiment with this, at some time in the future,
            but haven't tried it yet.

       (4) Use filters or wrappers. Didn't use because it looked to be
            too much work, and we didn't wan't to reject these messages,
            but wanted, unless this was legitimate "spam," contact the
            sender and help them be able to deliver to the intended

       (4) Try the sendmail list(s), e.g.:

            (Didn't need to, since we got more than enough help here!)

Thanks to (in order received - hope I didn't miss anyone):
      "Jeffrey K. Pado" <>
      Jochen Bern <bern@TI.Uni-Trier.DE> (Danny Johnson)
      Ian MacPhedran <Ian_MacPhedran@engr.USask.Ca>
      "Sergey Mokryshev" <>
      Andrew Mitchell <>
      Jim Harmon <> (Miquel Cabanas. BBM-UAB)
      Mark Baldwin <>


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