Question : 554_5.1.0_Sender_Denied

Basically, one user within the organization cant receive quite important emails from one domain. Our organization has website hosted by 3rd party which allows visitors submit an online application. Once they hit submit, the application (as an email) should be forwarded to appropriate person for further processing such as price quote etc.

I already spoke to their admin and they just keep receiving --> 554_5.1.0_Sender_Denied. Their system is set to send those requests as --> "[email protected]" with HTML and plain text attachement to our mail server.

I've done quite extensive research on this kind of error but no luck so far. Let me briefly describe my environment and settings i've done so far:

1. exchange 2003 patched, Symantec Mail Security for exchange - i dont see any emails from that domain being quarantined or such
2. i've configured Sender, Connection and Recipient Filtering in exchange (Global Settings\Message Delivery)
3. i made sure their domain isnt on the list in Sender Filtering
4. i've added their IP in Global Setting\Message Delivery\Connection Filtering\Accept
5. Recipient filtering i only ticked: Filter recipient who are not in Directory


any help much appreciated.
thx
Jesi

Answer : 554_5.1.0_Sender_Denied

Symantec Mail Security will sometimes deny a connection without putting the mail in quarantine I think.  I would start there.  I've moved away from that product and started using a service called Appriver to filter inbound mail for viruses and spam.  It works muct better in my opinion and is considerably less hastle to configure.  You might be familiar with Postini already, Appriver is similar.

Here are the possibilities as I see them for you:
1. Your firewall is filtering SMTP connections somehow.
2. Symantec, since it acts as a SMTP relay for your Exchange system is filtering the connections
3. Exchange itsself is filtering connections.

I would start at the outside and work my way in if I were you.  It seems like you've already checked a lot of the Exchange settings anyway.  If you haven't done sone already, restart your SMTP service after you made all those Exchange configuration changes.  It never hurts.  You can also try manually simulating a connection to your server from this individual using the Telnet program.  There's a Microsoft article at http://support.microsoft.com/kb/153119 that has a bit about using Telnet to troubleshoot mail connections.  You would of course need to initiate the Telnet from OUTSIDE your firewall to test.