Email server in DMZ

Morning all,

My setup is Red, Green and a Orange ( DMZ)

Red is x.x.x.43, Green is and Orange is

I have a mail server in the DMZ using ( DNS is )

I’ve been trying to get incoming mail directed to so have set rules for SMTP, POP3, IMAP Etc. set accordingly.

However I still receive no email - getting a reply that port 25 isn’t working.

If I change the ip of the mail server to x.x.x.43 and move it outside the firewall - it works as it should ( so to me that shows my DNS settings are correct but my firewall rules are not )

I’ve been through the wiki and nothing is any clearer - and it appears that my rules apart form the smtp are working as well - because i can access the email web front end from outside as well.

So, can anyone point me in the right direction ? All help gratefully accepted.


Do you have a destination nat rule to open port 25?

Apologies for time wasting - ISP took forever to update DNS settings - all good now