After migrated users from On-prem to O365, some users are receiving delivered notifications from emails that have been sent since 2017

Question

Hi Team,

After migrated users from On-prem to O365, some users are receiving delivered notifications from emails that have been sent since 2017. Do you know how to explain this?

Thank you for your help,
Rose

Answer 1

@J-3804

First, I want to confirm with you: whether all migrated mailboxes have this phenomenon? Whether this phenomenon occurs on all old emails?

You can use “Get-MessageTrace” and “Get-MessageTrackingLog” command to check from Exchange online and Exchange on-premises. We will know when and how the email was generated:

Get-MessageTrackingLog -Sender "MicrosoftExchange329e71ec88ae*******@domain.com" -Recipients "user@domain.com" -MessageSubject "Delivered: Test1234" | select EventID,source,Timestamp  

If there exist record about this email, it means email was processed twice, I would confirm with you whether there exist email filter tool in your organization which may cause this phenomenon.

If there doesn't exist related record, I think there may exist something wrong with the mailboxes, try to migrate mailbox to another database(It could repair some issue for mailbox) before migrating it to Exchange online.

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Answer 2

Will try that , Thank you for your help