This is a very common question, I will go on to explaining the differences between the incoming mail server and the outgoing mail server.

Incoming mail server: mail.yourdomain.com (port 110) –default

Outgoing mail server: mail.yourdomain.com (port 25) –default

* mail.yourdomain.com refers to your domain names mail server. The prefix is “mail” followed by .yourdomainame

Problem: When an e-mail is sent via the Internet it is routed through port 25. When an e-mail server that runs on your computer delivers messages, it always uses port 25 to transmit data to remote e-mail servers. Therefore, if your ISP is blocking the port, your messages will not get through. There are two different ways the port 25 to overcome this.

Resolution 1: Please note that many instances you will be able to receive e-mail but not receive e-mail, this is because many ISP (Internet service providers) block the port 25 cut down on the amount of spam that is sent from their networks. In order to find a way around this we use the ISP outgoing mail server. Here is a list (maybe incomplete) of outgoing mail servers.

Resolution 2: Contact your ISP & request that the port 25 block be removed from your account, a majority of ISPs will remove this block from your account while others may not.