Open Microsoft Outlook and select Tools => E-mail Accounts... from the menu. You wil be presented with this screen:



Click next and you see something like this:



Select the mail account you wish to change and click the change button, you will then see this:

Click the more settings button to see this:

Click the Advanced Tab to see this:

The port number you are concerned with is the Outgoing Server (SMTP): If this is currently set to port 25, you do not need to make any changes, you can if you wish, as it can help when you are travelling. If you are currently using port 366, please change this number to 587.

Click Ok until you are back to you mailbox. Congratulations Your Done!