Exim IPv6, port 25 closed but 465 and 587 open

I've recently been reconfiguring Exim to properly support my IPv6 setup. I'm using Exim 4.85 and recently rebuilt the exim.conf file, as some areas had changed since last setting it up.



I've noticed that after applying the new IPv6 settings, I cannot make a connection to port 25 on an IPv6 address but can on IPv4 addresses as normal. What's even more stranger is I can make an IPv6 connection on TCP 465 and 587. If I log into the box and run a telnet session at the IPv6 address to TCP 25, it will respond, but just won't externally.



My firewall is CSF and port 25 is listed in both TCP_IN/OUT and TCP6_IN/OUT. I tried dropping the firewall but connections still don't work. I checked which IP addresses Exim is bound to and everything looks correct. There is a specific bind setup for the IPv6 address I am trying to connect to externally on TCP 25



Due to certain requirements, Exim is sending from more than one IP, I have implemented the feature documented below (but manually control the two virtual files)



http://ift.tt/1I1X39F



This works fine, even IPv6 reverse DNS works (I was using an older method previously which didn't have IP6 support in mind)



Is there anything obvious in the exim.conf that I've missed as to why external connections to TCP 25 on IPv6 would fail like this? It suggests firewall, but disabling it doesn't make a difference and the correct allow rules should be set.



Thanks,



James

Exim IPv6, port 25 closed but 465 and 587 open