New minimum Outlook for Windows version requirements for Microsoft 365

StevenTater There could be 2 other reasons why Outlook 2013 may not be working for you. First being the use of Basic auth & its upcoming retirement. I'd highly recommend you to work thru the instructions in this article to enable Modern auth in your org and then switch the auth mechanism in use by Outlook 2013 to Modern auth, see: Enable Modern authentication for Office 2013 on Windows devices - Microsoft 365 admin | Microsoft Docs. Second being the use of Windows 7 as operating system, where Outlook 2013 is in use. If use of TLS 1.1 or 1.2 is not enabled at the OS system level, then you will see connectivity issues in Outlook 2013, check out this article for more info and solution: Outlook stops connecting on Windows 7 and legacy Windows versions (microsoft.com). Hope this helps!