Hello Experts!, I have a scenario that I need some help with:
#5.7.1 smtp;550 5.7.1 Unable to relay
We have an exchange server 2003 sp2. We have two email addresses for our users email@example.com and firstname.lastname@example.org. For the most part this has been working fine for the past couple of years.
Recently, we've been getting several external customers telling us that when they email us at the .net email address, they get a bounce back message, but they're able to send it to the .com email address with no problems. (we've only gotten this complaint from a handful of external customers from various companies). Here's what confuses me, it's not all or none---most customers can send to the .net and the .com,....only a select few external customers. at first, it thought it might be on the customers end, but now we're seeing several customers with the same issue---its looking more like its on our end. Any clues?
I've copied a bounce back message from one of the external customers:
Diagnostic information for administrators:
Generating server: 29smtp.domainA.com
#< #5.7.1 smtp;550 5.7.1 Unable to relay> #SMTP#
Original message headers:
Received: from 29caht1.domainA.com ([10.29.0.93]) by 29smtp.domainA.com
with Microsoft SMTPSVC(6.0.3790.3959); Mon, 8 Mar 2010 15:08:44 -0800
Received: from 29EXVIR1.domainA.com
([fe80:0000:0000:0000:2df2:c6b4:184.108.40.206]) by 29caht1.domainA.com
([10.29.0.93]) with mapi; Mon, 8 Mar 2010 15:08:39 -0800
From: Tim <email@example.com>
To: 'Chris' <Chris@domainB.net>
Date: Mon, 8 Mar 2010 15:08:39 -0800
Subject: Checking in . . .
Thread-Topic: Checking in . . .
X-OriginalArrivalTime: 08 Mar 2010 23:08:44.0251 (UTC) FILETIME=[4CD132B0:01CABF14]