Outlook Stuck on "Trying to Connect…" to Microsoft 365? Fix the Connection

Classic Outlook sits on Trying to connect… in the status bar and never settles on Connected, so mail won’t send or receive.

Why: Outlook can’t complete the handshake with the Exchange/Microsoft 365 server. The usual culprits are an out-of-date Outlook build, a corrupted profile, or an account that needs to re-sign-in — not your internet, if the web mailbox loads fine.

Fix 1: Confirm the mailbox works on the web first

This tells you whether the problem is Outlook or the service.

1. Open a browser, go to outlook.office.com, and sign in.
2. If the web mailbox loads and sends mail, the service is fine — the fault is in your Outlook client, so continue below.
3. If the web mailbox is also down, it’s your network or a service outage; nothing in Outlook will help until that clears.

Fix 2: Run the Microsoft 365 connectivity diagnostic

Microsoft has an automated tool that checks and fixes the most common Outlook connection faults for you.

1. On the affected Windows PC, select Start under Classic Outlook connectivity troubleshooter on Microsoft’s current troubleshooter page and allow it to launch Get Help. It requires Windows 10 or later and applies to classic Outlook, not new Outlook.
2. Follow the prompts to diagnose connectivity, sign-in or profile problems. Get Help replaces the downloadable Support and Recovery Assistant (SaRA); installing the old tool is not required.
3. Admins can additionally run the Outlook User Connectivity diagnostic from the Microsoft 365 admin center to test the account server-side.

Fix 3: Update Outlook and Windows

Out-of-date software is one of the two most common causes Microsoft calls out.

1. In Outlook: File → Office Account → Update Options → Update Now.
2. Run Windows Update and install everything pending, then restart.
3. Reopen Outlook and press F9 (Send/Receive All Folders) to retry the connection.

Fix 4: Rebuild the Outlook profile

A corrupted profile keeps Outlook stuck even when everything else is healthy.

1. Close Outlook. Open Control Panel → Mail (Microsoft Outlook) → Show Profiles.
2. Click Add, create a new profile, and add your account.
3. Set Always use this profile to the new one and open Outlook. If it connects, the old profile was the problem.

FAQ

Where do I get the diagnostic tool? Use Microsoft’s Outlook troubleshooter link on the support page to launch Get Help on the affected PC. SaRA’s desktop troubleshooting scenarios have been replaced; the Windows/client requirements matter.

My whole team is stuck connecting — is it me? If more than one person is affected, check the Microsoft 365 Service health dashboard (admin sign-in) for an Exchange Online incident before troubleshooting individual PCs.

Sources: Microsoft Learn — Fix Outlook connection problems in Microsoft 365

Additional sources: Microsoft — troubleshooters in Get Help