Microsoft server is not connecting to Mac mail

Hi Emma

Thank you for reaching out to the Microsoft Q&A Forum.

Based on your description, I understand that Apple Mail on your Mac is getting stuck on “downloading” and is unable to sync emails from your Exchange account.

To better understand the issue, could you please confirm: 

-Are you able to access your mailbox through a web browser? 

-Which macOS version are you currently using? 

In the meantime, you may try the following steps: 

1.Remove and re-add the Exchange account 

Go to System Settings > Internet Accounts, remove the Exchange account, then add it again and sign in. 

2.Check network connection 

Ensure your Mac has a stable internet connection and is not restricted by VPN or firewall settings. 

If the issue persists and the mailbox is not accessible via a web browser, you may consider checking with your IT administrator to verify the Exchange service status and configuration. 

Please understand that our initial reply may not always immediately resolve the issue. However, with your help and more detailed information, we can work together to find a solution.

Please feel free to share any updates. If I have misunderstood your scenario, kindly let me know and I’ll be happy to assist further.

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Use the following steps to troubleshoot the Exchange connection issue on Mac and get messages to download correctly.

1. Confirm Outlook/Mail is online

• In Outlook for Mac, on the Outlook menu, make sure Work Offline is not checked. If it is, clear it so Outlook can connect to the server.

2. Check the Exchange connection status

• In Outlook for Mac, go to Tools > Accounts.
• In the left pane, select the Exchange account.
• Look at the indicator icon next to the account:
  • If it is orange, there is a connection problem to the Exchange server.
• If the account has worked before, try accessing the same mailbox via another Exchange client such as Outlook on the web. If Outlook on the web also fails, contact the Exchange administrator to verify the server is online and healthy.

3. Verify server/SSL requirements

• Some Exchange environments require an encrypted (SSL) connection.
• In Outlook for Mac:
  1. Go to Tools > Accounts.
  2. Select the Exchange account in the left pane.
  3. Click Advanced, then the Server tab.
  4. Under Microsoft Exchange and Directory service, ensure Use SSL to connect is selected if required by the Exchange administrator.
• If SSL/TLS settings on the Exchange server were recently changed (for example, SSL disabled), the server may need to be configured in “Compatible mode” so Outlook for Mac can negotiate from SSL to TLS. This must be done on the Exchange/edge or TMG server by the administrator, following the guidance in KB 980436.

4. Check for network/firewall or proxy issues

• If using POP/IMAP or if the environment uses a proxy:
  • Confirm with the network or Exchange administrator whether a proxy server is required to reach the mail server.
  • If a mail proxy is required, configure it in macOS System Preferences as provided by the administrator.
  • If a firewall is in place, the ISP or network admin may need to allow or provide an alternative SMTP/IMAP/Exchange endpoint.

5. Clear a potentially corrupted cache (Exchange folders) If only some folders never finish “downloading” and the server is otherwise reachable, the local cache may be corrupted.

Caution: Emptying the cache removes any items that exist only locally and are not synchronized to the Exchange server (for example, unsynced changes or certificates). Ensure important data is backed up first.

To empty the cache for a problematic Exchange folder in Outlook for Mac:

1. Make sure the Mac is connected to the Exchange server (no orange status on the account).
2. In the navigation pane, Ctrl+click or right‑click the affected Exchange folder (for example, Inbox or Sent Items) and select Properties.
3. On the General tab, choose Empty Cache.
4. Outlook will clear the local copy and automatically re-download items from the Exchange server. The “downloading” status should complete once synchronization finishes.

If, after these steps, the account still cannot download messages while Outlook on the web works correctly, the Exchange administrator should review server-side SSL/TLS configuration and any reverse proxy or TMG settings that might be blocking or breaking Outlook for Mac connections.

References:

• I'm not receiving email or other items in my Exchange account in Outlook for Mac
• I can't connect to my Exchange account in Outlook for Mac
• Outlook for Mac clients cannot connect to Exchange Server
• I can't send or receive messages with Outlook for Mac