PLEASE READ:SMTP forwarder isn't forwarding messages with "return -path <>".

  • From: Lenny Burns <lenny.burns@xxxxxxxxxx>
  • To: "'[ExchangeList]'" <exchangelist@xxxxxxxxxxxxx>
  • Date: Tue, 28 Jan 2003 18:36:08 -0500

I have posted this several times using various descriptions of the problem.


I have researched this situation everywhere and still nothing works.

I put my exchange server inside the firewall and used a IIS5 (windows 2000)
SMTP server to FORWARD MAIL to it.

Only remote domains in the list that I entered are forwarded.
I specified the exchange server IP in []'s for each remote forwarded domain.

ALL email is forwarded now.

I have not installed virus or Spam filtration software on the forwarder.

All seemed fine, until I realized that all INBOUND emails with a
"return-path: <>" in the header are being dropped in BADMAIL.

I look on the event log of the forwarder, and see:
Event Type:     Warning
Event Source:   smtpsvc
Event Category: None
Event ID:       4000
Date:           1/28/2003
Time:           6:16:54 PM
User:           N/A
Computer:       MAILGUARD
Message delivery to the remote domain '' failed for the following
reason: Unable to successfully connect to the remote server.
0000: 3a 02 04 c0               :..À    

This happens once for every message with a "return-path: <>" in the header

Further research revealed that these messages are NDRs from AOL but MOSTLY
messages from List servers.

We NEED to get these emails!!!

So, here's what testing I have done..

If I drop these messages into the PICKUP folder, they get delivered.

I telnetted into the local host for the forwarder, sent a message from <> to
It arrived.

I telnetted into the exchange server, sent a message from <> to myself.
It arrived.

(I am assuming these emails are the same as the ones that have a
"return-path: <>" in them.)

I send a message to the foreign list server with a command that makes it
reply, and it too lands in BADMAIL.

If email arrives from an exterior server with "return-path: <>" in the
header, it drops to badmail and I cant stop it.

What should I do?

Im completely stumped, and this has been going on for over a month now.

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