I keep receiving the following error message on my Win2003 IIS 6.0 SMTP
server, when trying to relay mail to an Exchange 2003 server on my network.
This error only appears when trying to send to the specific domain hosted on
the Exchange server, and does not appear when sending mail to other domains.
I am sending from the address DO_NOT_REPLY@<domain.com>, which an account
does not exist for, but again, it works fine for other domains. Any ideas?

--------------- Begin error message from System Event Log -----------------
Message delivery to the host '<exchange 2003 server IP>' failed while
delivering to the remote domain '<domain.com>' for the following reason: An
SMTP protocol error occurred.
The SMTP verb which caused the error is 'MAIL'.  The response from the
remote server is '553 Terminating connection as the sender is spoofed.
'.
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I forgot to mention.. I have setup Exchange 2003 to allow relaying from the
IP address of the web server (under Default SMTP Virtual Server > Relay).

"James M." wrote:

> I keep receiving the following error message on my Win2003 IIS 6.0 SMTP
> server, when trying to relay mail to an Exchange 2003 server on my network
.
> This error only appears when trying to send to the specific domain hosted 
on
> the Exchange server, and does not appear when sending mail to other domain
s.
> I am sending from the address DO_NOT_REPLY@<domain.com>, which an account
> does not exist for, but again, it works fine for other domains. Any ideas?
>
> --------------- Begin error message from System Event Log ----------------
-
> Message delivery to the host '<exchange 2003 server IP>' failed while
> delivering to the remote domain '<domain.com>' for the following reason: A
n
> SMTP protocol error occurred.
>  The SMTP verb which caused the error is 'MAIL'.  The response from the
> remote server is '553 Terminating connection as the sender is spoofed.
> '.
> ----------------------------------------------------------------------------------
---

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