I've encountered al problem lately, at the beginning of the week I received several emails like this when sending mails...
Your message did not reach some or all of the intended recipients.
Sent: 9/04/2006 14:37
The following recipient(s) could not be reached:
email@example.com on 9/04/2006 14:37
There was a SMTP communication problem with the recipient's email server. Please contact your system administrator.
<mydomain.be #5.5.0 smtp;551 Mail from your IP is currently blocked based on RBL listing>
I've contacted my ISP and apparantly my IP has been blocked so I requested to unblock it and to be sure I changed the IP of my mail server onto another one. To be sure that my exchange wasn't an open relay I performed some tests (as described in other topics as well) and apparantely only authenticated users can connect to the mail-server... (Tests from autside using telnet gave the "connection failed" error).
But now, a few days later, I get these error mails again... but now for the second (fixed btw) IP-address. When checking several blacklists (http://www.robtex.com/r/18.104.22.168.html
) I saw that it was listed again.... But now I have no clue what to do to prevent from being blocked again...
I'm quite desperate as my mailserver has been up and running several months now without any error uptil now... I don't get it.
Thanks for the help !