Some users of our Exchange server have been unable to send to a few different domains this week. They received the following message:
email@example.com on 10/20/2006 9:36 AM
There was a SMTP communication problem with the recipient's email server. Please contact your system administrator.
<mail.ourdomain.com #5.5.0 smtp;550 Service unavailable; Client host [208.178.XXX.117] blocked using 88.blacklist.zap; Mail From IP Banned>
(I have changed the email addresses and IP addresses in the message above except for 88.blacklist.zap)
I am familiar with RBLs and have run our mail server's IP through several multi-rbl lists checkers such as http://www.robtex.com/rbls.html
. We're only listed in BLARSBL (http://www.blars.org/errors/block.html
) which appears to be a list that nobody actually uses.
I've googled for 88.blacklist.zap and found NOTHING. I've also searched for blacklist.zap and found other people reporting bounced emails similar to mine, but resulting from a list called ip.blacklist.zap. Thus far I haven't found any information about any real rbl named 88.blacklist.zap or ip.blacklist.zap.
The server also passed the open relay test at http://email-test.com/cgi-bin/webtestmail?cmd=show_openrelay
So my question is, what is actually causing these emails to be returned with this particular message? Can anyone identify this blacklist.zap and help me take actions to stop emails from bouncing back?
Thanks in advance!