[Exim] Mail Loop with Null Senders and Oracle WorkFlow

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Author: Kevin Reed
Date:  
To: exim-users
Subject: [Exim] Mail Loop with Null Senders and Oracle WorkFlow
Last week we had the fun of having a mail loop that was caused by the use
of a Oracle Workflow mailer and any bounce message sent back to it.

After I killed it (only 1600 messages looped), I started looking to how it
happened. Finally I figured it out and did some tests and found that is
is very easy to do. So I suppose if you have this critter on your systems
somewhere, you might want to check it out.

The problem is that Oracle Workflow deals with getting email back to it
via an Imap interface. When a message is sent out, it leaves the Unix box
it is on, hits the hub, the hub sends it to our gateway server and out to
the Internet...

If a bounce of any kind come back, it is received by the gateway, funneled
into the hub, routed to the Exchange server and deposited into a WFM
mailbox. The Oracle WorkFlow system then picks up the message via imap
and ... replies to anything sent to it. Real Cute.

The fact that the message was obtained from a mailbox via imap, apparently
is the problem since the fact it was a NULL sender (bounce) is lost.

The fix was to come up with a router that checked for a Null Sender and
the 3 special WFM mail accounts (Test, Dev and Prod) and reroute them to a
different human only read Exchange mailbox which I called FINAIR .

Now the people who need to know can see what bounce messages they get like
user not found, over quote, out of office etc... but it never gets back to
the WFM system.

I used a router like:

    Reroute_WFM:
         driver = redirect
         data = FINAIR@???
         senders = :
         local_parts = WFM_FINTEST : \
                       WFM_FINDEV : \
                       WFM_FINPROD
         domains = example.com


--
Kevin W. Reed - TNET Services, Inc.
Unoffical Exim MTA Info Forums - http://exim.got-there.com/forums