Microsoft has accepted that there’s a bug in Outlook Classic. Users can shift to the Semi Annual channel as a temporary fix.

If you're facing intermittent connectivity issues with classic Outlook, use the Classic Outlook Connectivity Troubleshooter to resolve them.

If you encounter issues while launching Outlook, this article will show you how to use Outlook Startup Troubleshooter to fix Outlook startup issues.

Microsoft to enforce strict email authentication rules for Outlook.com users on May 5 — what you need to know.