How to Fix Outlook for Mac Sync Errors

outlook for mac sync error


MS Outlook becomes the face of an Exchange Server account by connecting its mailbox with itself. MS Outlook works on Windows and Outlook for Mac works on macOS platforms. If you are using an Apple computer, then it does not mean that it will not connect with MS Exchange Server. Outlook for Mac will connect and synchronize the mailbox and show the folders like inbox, outbox, sent items, etc.

How does Outlook for Mac connect with Exchange?

Outlook for Mac shows the Exchange option while connecting an account. Here is the basic process to add the Exchange account to the application-

  1. In Outlook for Mac application, click on Tools and choose Accounts>>Add email account.
  2. Input the email address of the Exchange Server on-premises account and choose the Next option.
  3. Choose Not IMAP/POP and select Exchange.
  4. Now, you must provide the following details of the Exchange account;
  • Email Address – The complete address of the Exchange account with the full domain name. Example – DomainName\username.
  • Password – The password of the Exchange account.
  • Server – Full server name. But, it is an optional field.
  1. After providing the details, click Add Account and Outlook will try to establish the connection. If the details are correct and Exchange Server is accessible, then the account will be connected successfully.


The application gets a synchronized version of the mailbox when the Exchange account gets a connection with Outlook for Mac. It requires a constant connection to allow email communication and it is a common scenario where a user finds that Outlook for Mac is not syncing with Exchange Server.

Various Causes & Resolution of Outlook for MAC Sync Errors

There are multiple causes and their relevant resolutions that you should know to make the connection again. We will check each cause and its functional resolution.

Cause-1. The Exchange account credentials are either incorrect or changed.

The Exchange Administrators like to update their account’s security settings by changing the password and access control routinely. If the Administrator has changed the password, then you should ask for it and update it in Outlook.

  1. Choose Tools>>Accounts.
  2. Choose the Exchange account and open it to verify its credentials.
  3. Input the credentials again and try to reconnect the account with the application.

Cause-2. The user has set the functional mode to offline.

Sometimes, a user changes the Outlook mode to offline to stop getting emails anymore and work on some non-email tasks. It is easy to change the method to Online again.

  1. On the Outlook menu, see if the Work Offline option is checked.
  2. If it is checked, uncheck it and the account will become online again.

Cause-3. The Exchange Server is unavailable.

It is a rare occurrence when Exchange Server is down and the email client finds itself disconnected from Server. It is not an error and you can contact with Exchange Administrator to determine the correct solution.

  1. Click Tools>>Accounts.
  2. If the Exchange account is not connected to the server, then its status will be shown in orange color.

Cause-4. Cache data is incomplete.

Cache data is created for each account and the overall cache created for all accounts can become great in size or some parts may be incomplete. If you can delete the cache and restart the application, then the account will find it easier to connect with Exchange again.

  1. Right-click on Exchange account in the account list and choose Properties.
  2. Go to the General tab and click on the Empty Cache button.
  3. Click OK to close the Properties window.

Cause-5. Outlook for Mac is outdated.

Microsoft updates Exchange Server and email clients regularly and the older versions become outdated. Generally, businesses do not update Outlook clients until Microsoft stops supporting the current version of the application. So, you should update Exchange Server to its newest version.

  1. In Outlook for Mac, go to the Help menu and choose ‘Check for Updates.’
  2. The AutoUpdate window will prompt the update window and show you if any update is present.
  3. Download and Install the updates and restart the application.


The resolutions to connect Outlook for Mac with Exchange Server work well when the account is healthy and its OLM file is connected with the account. If the data file is corrupt, then the errors will continue to bother you after running all methods. For a full recovery, you must use professional OLM Repair software that can scan the data file for corruption and recover the mailbox.

Download OLM Repair Tool from Stellar


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