Changing the outgoing port number is a necessary step in troubleshooting your email programs. For example,

  • Your email client has not been sending since the initial setup.
  • Or, if your email program suddenly stops sending or receiving regular emails.

Common indications that the outgoing port number of your email programs requires an update:

  • You can still receive email but an error appears when you send messages. Verify that the outgoing server name is typed correctly.
    • The error may say that the software is unable to connect to your outgoing server and to contact your service administrator or Internet service provider.
  • Your messages are starting to gather in the outbox but you are not getting any noticeable errors.

In both scenarios, the cause can be that the outgoing port number is incorrect or blocked. There are many Internet Service Providers that are now blocking the default outgoing port that many email clients set up automatically—port 25.

They do this to protect users from spam and viruses that direct infected machines to send through the default ports. Changing the port to either 2525 or 587 will usually resolve the issue.

Your internal virus scanning system or firewall may do the same out of taking an action to protect the machine.