Hi, One of our clients has noticed, that when he is using our server as SMTP an interesting line appears in message header - X-PopBeforeSMTPSenders, which contains all mail accounts that this user has. Here is sample: X-PopBeforeSMTPSenders: email@example.com,firstname.lastname@example.org,email@example.com Server is running WHM 10.1.0 cPanel 10.2.0-R52, Fedora i686 - WHM X v3.1.0. I asked him to use another server for SMTP and then that line is not added. Does anyone else got into this? How can I remove this line? Thanks! Anton.