Someone placed a SPAM complaint to MAPS (rbl.mail-abuse.org) about a SPAM server on the same class C as my server is on. MAPS placed a blanket /24 block which abviously affects my server (aaaargghhh!!!).
I have contacted MAPS and asked them to either whitelist my IPs or remove /24 block. One of their "investigators" gave me a canned answer that I have to contact my ISP to resolve that issue. He did not even read the email I sent him! I have responded that I am the ISP, but have not received anything back. Meanwhile emails of my users bounce...
I must admit it is the first time for me Anyone has any experience with dealing with this kind of issue?
MAPS must have had its reasons to block an entire /24. Probably because there is a hard time spammer in that range (plus a non responsive ISP). Contact your (colo-)provider, or whoever gave you the IP address(es) and let them boot the spammer off the network.
Then explain to MAPS that the issue has been resolved.