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VB365 - Unable to Restore Email to Mailbox

  • June 25, 2026
  • 5 comments
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I am testing out deleting and restoring a single email in my Exchange Online mailbox using V365 restore with modern authentication. I keep receiving an error of ‘failed to open mailbox, account doesn’t have permission to impersonate requester.’

I found that adding the Impersonation role in exchange is depreciated, so instead I installed Exchange Online Powershell, connected to ExchangeOnline, and granted my 365 admin account full access to my mailbox and I can now see my 365 account as a full delegate in my mailbox settings. I did this because my 365 account was not an option when adding delegate through EAC, I assume because it has no Office license or mailbox so it is not in the list of users to add as delegate.

However, even though I can now see my 365 account has full access to mailbox, I continue to get error when going through restore wizard and entering my credentials and 2FA code.

Is there anything more I need to do or am missing about granting my 365 admin account access to user mailboxes?  Thanks!

Best answer by Chris.Childerhose

Also check the links at the bottom of this KB - KB4708: Assignment of the ApplicationImpersonation Role Fails With Error

5 comments

Chris.Childerhose
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I assume you are using VB365 8.4 as the version?  I am not seeing anything that jumps out but will keep looking, but a support ticket might help get to a resolution faster as they can check the logs.


Chris.Childerhose
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  • Veeam Legend, Veeam Vanguard
  • Answer
  • June 25, 2026

Also check the links at the bottom of this KB - KB4708: Assignment of the ApplicationImpersonation Role Fails With Error


  • Author
  • Comes here often
  • June 25, 2026

Thanks Chris! I’ll check out the links and email support if needed. I am on 8.4.0.1457. I did try certificate based authentication, but receiving errors on those. Also not sure what cert to use, it shows a long list of the same Veeam certs with different names but the ones I tried all gave an error.


  • Author
  • Comes here often
  • June 25, 2026

I had about a dozen or more Veeam certs to choose from for certificate authentication and every one I tried was failing, but I decided I might as well try every single one before creating a support ticket and the final one in the list worked! It’s had the same name ‘Veeam Software’ as many other certs in the list, but the one that worked had the friendly name of Veeam Software Group GmbH certificate. After selecting that I was able to proceed and restore the email to my inbox. 

I probably would have given up going the certificate route if I didn’t see that link you provided, so thank you Chris! Now to continue on with testing the restoration of an entire mailbox. 🤞


Chris.Childerhose
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Great, glad to hear that it was just a cert and nothing major.  Glad you got it working and happy testing.