I am receiving a bounce back from yahoo addresses when users try to email firstname.lastname@example.org
I am using Exchange Server on WIndows SBS 2003.
Your message did not reach some or all of the intended recipients.
Subject: Testin email
Sent: 1/23/2008 11:58 AM
The following recipient(s) could not be reached:
email@example.com on 1/25/2008 9:52 AM
There was a SMTP communication problem with the recipient's email server. Please contact your system administrator.
<midsouthsteel.net #5.5.0 smtp;553 Mail from firstname.lastname@example.org not allowed - >