Unable to connect to mail server

Check to be sure TLS 1.2 is now enabled:
1. Open the Start Menu.
2. Search for “internet options”
3. Click on the search result titled Internet Options
4. Navigate to the Advanced section
5. In the area under Settings, scroll down to the Security section and make sure that the Use SSL 2.0, Use SSL 3.0, and Use TLS 1.0 options are disabled (don’t have a checkmark beside them) and that the Use TLS 1.1 and Use TLS 1.2 options are enabled (have a checkmark beside them).
6. Click on Apply, then click on OK

https://clients.websavers.ca/whmcs/knowledgebase/262/Unable-to-connect-to-mail-servers-using-Outlook-on-Windows-7-or-8.html