Exchange SBS2k3 - unable to send external mail, IP not authorized

[giantcrazy]

Hi all-

Sorry if this question's been covered - I tried searching Technet, the web, the forum, my gym shorts and everything else, but couldn't come up with an answer.

I have a version of SBS2k3 that I'm running in a VMWare workstatino as a test. We're a small company (5 employees) that recently moved to Windows Mobile phones, and would like to take advantage of Direct Sync for push e-mail.

This is only a test - nothing mission critical, we figured we'd use a toy domain first before migrating our mail server (which is currently UNIX based and hosted).

I changed the MX record, installed SBS2k3, and ran through the wizards. First test was an inbound e-mail from an external source, and it worked like a charm.

Thinking that the hardest part would be getting mail from the outside, I tried an outbound external e-mail test, and it failed with the following error:

**********
There was a SMTP communication problem with the recipient's email server. Please contact your system administrator.
**********

From what I've been able to read, it seems like there's a permissions problem somewhere. Anywhere I could, I added the IP address of the internal network (the workstation's behind a NATing firewall with only port 25 open to it), but to no avail.

Any ideas where I should turn next?

Thanks,
-John

 

[giantcrazy]

D'oh - the error message truncated. It was as follows:

There was a SMTP communication problem with the recipient's email server. Please contact your system administrator.
<---------.com #5.5.0 smtp;550-5.7.1 [(public IP)] The IP you're using to send email is not authorized >

 

[giantcrazy]

Alright, I might be talking to myself, but I figured I'd update since I found the solution.

I was missing a reverse-ARP entry on the server. Added one pointing back to the box, and mail finally started delivering for the troubled domains (AOL, gmail).