Hello,
I'm having a very strange blocking issue for a while now. I run CSF firewall on some cPanel servers and CSF blocks some of the mobile users (on mobile networks) that are using e-mail accounts. What's strange is that I cannot find their IP addresses in any blocklist but after flushing all blocks the users can connect to the mail server again.
I even saved the block list, unblocked and search the connecting IP and cannot find any entry.
How can I find the reason it's blocking them and solve this issue? This happened on multiple servers, so it's not isolated. It always happens to the same users (or at least the ones that I know of).
Please help! Thanks!