I would like to use a home email server. I have my own domain name to use. I am using Dynu's dynamic service to forward everything to my home IP address. My provider blocks some ports including some email ports. How can I bypass this restriction?
Night

My ISP blocks port 25. Many do. This is supposed to help stop spammers. (In my opinion it is to try to get you to get their business service. The down side is the price, the up side is a Static IP address so you don't need DDNS.)

The OUTBOUND solution is a Mail Relay Service.
These services have their own "selection" of ports that they can use. (I use Dynu's 2525)
Just be sure to set port forwarding in your router. Private port 25 to your server IP, and the chosen port from your Relay service to be the Public port.

The INBOUND solution is a Mail Forwarding Service (or a store & forward version).
The key here is to setup the "Name Server" information to that specified by your Service.

I had great success with these 2 mail services with my old domain service. I'm caught in the middle of the 5 days for transferring my domain to Dynu, and am having mixed results with theirs. I canceled those services with my old domain when I set the same services up at Dynu. Warning: BAD IDEA ! If you are transferring your domain, keep your relay service, and forwarding service until the domain transfer is complete.