We were having a problem with mail from a handfull of users bouncing
with the message below:

Diagnostic-Code: smtp;554 5.6.1 Body type not supported by Remote Host

The strage thins was that mail from some users in a sending domain
worked while mail from others did not.

after investigating newgroups and the like, everything was related to
configurations other than our own. most point to 8bit MIME issues.

We are set up as such

internet mx record = IIS6 based SMTP on DMZ --> forwards/relays to -->
Exchange 2003 Frontend server --> delivers to --> Exchange 03 Bakcend
server.

Our problem was due to a setting in the IIS6 based SMTP server we use
to relay. When we set up our relay domains in the domains tab under:
MMC - IIS - Deafult SMTP Server - domains

We checked the box to send HELO instead of EHLO, once we unchecked
this box the bouncing E-mails stopped.

Wer are under the assumtion that our relay was advertising EHLO and
accpting it , but then was unable to relay it because we had crippled
it down to HELO between itself and our exchange servers.

Hope this saves someone else some time.

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