Exchange SMTP Relay Error

[JoshuaTree1]

I manage a Windows 2003 SBS w/Exchange SP2 server. I'm trying to get Outlook Express to connect from an off-site location (IMAP/SMTP). I get IMAP folders and download mail fine. When I try to send an e-mail to an outside domain I get an SMTP error "550 5.7.1 unable to relay for *@*.com".

I understand that non-authenticated clients should not be able to relay, but I am trying to authenticate. I have tried all the security options I can think of ("outgoing mail server - requires authentication", etc.).

On the server side I have selected the virtual SMTP server option "allow all computers which successfully authenticate to relay". For authentication type I have enabled anonymous, basic authentication, and Integrated Windows Authentication.

I've disabled Symantec AntiVirus on the server and client for testing purposes.

What am I missing???

 

[Marcs41]

If you are playing with Outlook Express to connect to an Exchange Server, you would be far better of to use OWA!

Marc
_{If 'something' 'somewhere' gives 'some' error, expect random guesses or no replies at all.
Free Tip: The F1 Key does NOT destroy your PC!}

 

[JoshuaTree1]

Yeah, I hate POP and IMAP myself so I wouldn't use it unless I had to. This exercise I'm going through is for the owner of a small business that has an iPhone. I could get it to receive mail but not send (with exchange), so I setup Outlook Express with IMAP to test the problem. Once I get Outlook Express working I should be able to get the iPhone running. People send mail through Exchange SMTP servers every day so I've got to be missing something simple...

Does anyone have any pointers on how I can get SMTP working per my original post?

Thanks!

 

[JoshuaTree1]

I figured the problem out. The issue was that the PIX 505 firewall had fixup enabled on SMTP 25. This was keeping outside mail clients from authenticating with the Exchange server. I new the firewall was passing mail on port 25 so I didn't initially think it could be the problem.

For anyone else that runs across this, I disabled it in the PIX by running the command "no fixup protocol smtp 25" and saving the config.

Time to go read about fixup to see if I've just opened an unacceptable security hole!!!

Now the server accepts inbound mail from anonymous connections (required to receive mail from the Internet). But for an outside mail client to relay to another domain, authentication is required (so this is not an "open relay").

Hope this info helps someone else.