What are the main causes of error 0x8004210B in Outlook?

Asked 25-Jan-2022
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1 Answer


Corrupted Outlook profile - This error message could be the result of a corrupted Outlook email account. Outlook will be unable to connect to the server if files in your Outlook profile become corrupted. You should be able to fix the problem by re-adding the email account via the Mail window, which will force the application to build a new profile.

The email has become stuck in the sending process — This error code may also appear if the procedure times out owing to a corrupted or huge attachment that cannot be properly processed. If this is the case, the only solution is to put the app in Work offline mode and remove the email that has become stuck.