I have just been reported that suddenly my users are not able to send email messages to few compaines. They are getting the following automated email message:
Your message did not reach some or all of the intended recipients.
Subject: FW: xxxx
Sent: 01/12/2007 13:48
The following recipient(s) cannot be reached:
xxx on 01/12/2007 13:48
There was a SMTP communication problem with the recipient's email server. Please contact your system administrator.
< my mail server name #5.5.0 smtp;553-Message filtered. Please see the FAQs section on spam>
Now I have the following concerns:
1) What do I need to check for such an issue?
2) How can I check if my IP is not black listed ?