I was changing IP addresses for my Exchage servers. After that I get this error every time when I try to send email to domains who are not on my exchange server:
Your message did not reach some or all of the intended recipients.
Subject: Test message
Sent: 12.7.2009 23:07
The following recipient(s) cannot be reached:
firstname.lastname@example.org on 12.7.2009 23:07
There was a SMTP communication problem with the recipient's email server. Please contact your system administrator.
<dora.tsc.is #5.5.0 smtp;550 #5.7.1 Your access to submit messages to this e-mail system has been rejected.>