Hi @Harry Matthews ,
Welcome to our forum!
Since the support for Office 2010 ended on October 13, 2020, and there will be no extensions and extended security updates, you can still use your office programs. For your better user experience, it is recommended that you use a newer version of office. For more information, please refer to: End of support for Office 2010.
Based on my research on the error "0x800401OF", i found that this issue is caused by the corrupted Outlook profile. You can try to create a new profile to resolve the issue. Please follow the steps mentioned in the below official article: Error 0x8004010F when you try to send or receive email in Outlook 2010 or Outlook 2013.
Hope to help you!
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