Why a Clean cPanel Mail Server Landed on Spamhaus XBL — Exim Sender Verify Callouts
A cPanel mail server jumped from one blacklist to four overnight. The queue was empty, the senders were normal and nothing on the box talked to port 25 except Exim. The cause was a single Exim option that makes your server knock on spammers’ doors. Here is how to find it, fix it and get delisted.