Hi Adam,

You can follow the below steps:

1. In Outlook, go to account settings. In Outlook 2010, I click File > Account Settings > Account Settings (again, it may be slightly different for Outlook 2016, but you should be able to find your way)


2. This should bring up a window showing all of your email accounts like this:


3. Double-click on the email address you want to fix. That will open a “Change Account” window that looks like this:


4. Click the “More Settings” button, which will open a window an “Internet email settings” window. Click on the “Advanced” tab. If the Outgoing server port say “25”, change it to 587. If it says “587”, change it to 25. Then click the “OK” button.


5. You’ll then be back at the Change Account window. Make sure “Test account settings by clicking the Next button” is checked, then click the Next button:


6. Outlook will attempt to connect to the email server and do a test receive, as well as a test send. If you get green checks for each, you’re good.

7. Click the “Close” button, which will take you to a “Congratulations” message in the Change Account window. Click “Finish”:

I hope this helps.

Regards,
Lokesh