Can messages be delivered on non standard ports?

Yes, MX Guarddog can deliver your email on any valid TCP/IP port.

Public email servers connect on port 25 when delivering a message, without exception. Two email servers exchanging email must speak the same language, and the language they speak functions on port 25. MX Guarddog will only accept incoming email on port 25, but outgoing email we can transmit on any port you wish.

There are two primary reasons you may want to deliver email on a non standard port.

• Your ISP blocks you from running your own email server - so they lock port 25.
• Email server hardening.

If you wish to run a mail server and your ISP blocks port 25, you can use MX Guarddog to accept your incoming email. In your domain center you can configure the port address of your email server. For example, you want to operate your email server on port 2525 (which your ISP does not block) we can accept your incoming email on port 25 and forward to you on port 2525 which gets around your ISP block.

The second reason to operate on a non standard port is to keep out persistent spammers. Spammers know email is sent on port 25, so they will sometimes connect to port 25 of a server they think 'may' be running an email server. If they establish a connection they can try and send spam. Spammers do not play by any set of rules, they break as many rules as necessary to try and get their junk mail delivered. If you operate your server on a port other than 25, it significantly reduces the changes of a spammer making direct delivery attempts to your server.