I am running Exchange Server 2003 to handle my companies e-mail needs. I am experiencing a problem with sending e-mail to certain addresses. I can send e-mail to addresses like hotmail or yahoo or big ones like that, but i am trying to send e-mails to people that have smaller ISP's that offer e-mail service and they are being rejected somehow. What could be causing this and how can I fix it so that we can communicate with all e-mail addresses and not just some? I have checked to see if my server IP is blacklisted and it is not so that is not the issue. I have attached the response that I get from the auotmated System Administrator.
Your message did not reach some or all of the intended recipients.
Subject: Test E-Mail
Sent: 10/16/2008 1:31 PM
The following recipient(s) cannot be reached:
'firstname.lastname@example.org' on 10/18/2008 1:38 PM
Could not deliver the message in the time limit specified. Please retry or contact your administrator.