can we restore mailbox/emails from Exchnage 2013 .edb/on-prem servers, after mailbox migrated to O365

Satya Datla 96 Reputation points
2021-12-15T09:49:24.527+00:00

Dear Experts, we are in critical situation and need to restore a mailbox/emails of a migrated mailbox to Exchange online, which was then deleted more than 3months ago.

we are in hybrid environment where this mailbox was migrated from on-prem Exchange 2013 server four months ago, since it was deleted months ago from Exchange online and there is no way we can recover it, is there a chance we can restore the mailbox/emails from on-onprem server via .edb file which used to be on-prem? does the mailbox gets deleted from on-prem server after migrating to Exchange online?

any suggestions or tips will be highly appreciated.

Microsoft Exchange Hybrid Management
Microsoft Exchange Hybrid Management
Microsoft Exchange: Microsoft messaging and collaboration software.Hybrid Management: Organizing, handling, directing or controlling hybrid deployments.
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  1. Andy David - MVP 137.9K Reputation points MVP
    2021-12-15T12:46:51.503+00:00

    It gets soft deleted on-prem - however the soft deletion time is by default only 30 days unless you changed it or the mailbox is on hold
    https://learn.microsoft.com/en-us/exchange/recipients/disconnected-mailboxes/disconnected-mailboxes?view=exchserver-2019

    See this section on how to work with soft-deleted mailboxes:

    https://learn.microsoft.com/en-us/exchange/recipients/disconnected-mailboxes/disconnected-mailboxes?view=exchserver-2019#working-with-soft-deleted-mailboxes

    https://learn.microsoft.com/en-us/exchange/recipients/disconnected-mailboxes/connect-disabled-mailboxes?view=exchserver-2019

    You can run this to see if any disconnected mailboxes still exist on prem:

    $dbs = Get-MailboxDatabase  
    $dbs | foreach {Get-MailboxStatistics -Database $_.DistinguishedName} | where {$_.DisplayName -eq "<DisplayName>"} | Format-List DisplayName,Database,DisconnectReason
    

  2. Andy David - MVP 137.9K Reputation points MVP
    2021-12-15T13:19:32.62+00:00

    If the retention period time is 60 days, its gone :(

    The edb is large because the white space is not reclaimed and the file on disk doesnt shrink even if all the data is removed.

    You only other option would be to restore an edb file from that time period and recover the mailbox that way

    https://learn.microsoft.com/en-us/exchange/high-availability/disaster-recovery/restore-data-using-recovery-dbs?view=exchserver-2019