You may not see the next option during your set up, especially if you have added the email address in the past. Don't worry in most cases this will mean the settings are stored.
If you do need to make changes to the outgoing port settings:
Click on Mail
, then on Preferences
. You can now select your account, click on the SMTP drop down list and click Edit SMTP Server List...
from here you can amend the outgoing port options.
8. Enter the port as 25
Unheck Use SSL
and set the authentication type to Password
Once these options have been set click the Next