IP not in csf.deny but email not working

[dotincnet]

Long time user.

3 servers. all running CSF

1 server IP is not blocked but emails not working on all email clients.
ALLOW that IP and the email starts working.

What is the fix/issue?

the only difference was this server was set up as with SSH on a different port than default.

Is anyone else having this issue?

Thanks.
Mike

[dotincnet]

update:
when adding CC_DENY : IN (india) in CSF Firewall settings , it adds 64.0.0.0/2 to the CC_DENY for some reason. we are using MaxMind