Since the release of Windows 10 there have been many reports of people unable to send mail after the update/upgrade. Mostly customers using Microsoft® Outlook® are the one affected by this issue.
Regardless of what outbound port changes are made Outlook® will throw back an error about not being able to connect to the network or mail server.
Thankfully there is a relatively simple fix for this:
1) Close Outlook® and any open applications
2) Press the key combination: Windows key x (hold down the Windows key and press the letter X - then release both)
3) Select the option: Command Prompt (Admin)
4) Type in: sfc /scannow
5) Hit enter
6) Let the scan complete
7) Re-run the scan until there are no errors reported (some people are reporting they had to run the scan twice)
8) Type: exit
9) Hit enter
Restart the machine - open Outlook® - the issue should now be resolved.