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Due to a mistake on a retention policy, too many (too recent) messages of user mailboxes were moved to online archive. I know that MS offers no wayback for online archive. I investigated some options:

  1. Deleting the archive and importing it back to the primary mailbox: I can't do, because some mailboxes were completely full at the time of archiving and now there's no room for merging
  2. Exporting archive to PST; reimport it to primary mailbox, filtered by date; delete and recreate archive; reimport the remaining of PST to archive: may work but it's a huge effort
  3. In an old post I found that there was a PS script, leveraging EWS, that was able to move selected items to archive. While wondering if it could do the reverse path, I found out that the script is no longer present in Powershell Gallery.

Other ideas?

Massimo
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1 Answers1

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I suggest you disable the retention policy for the mailbox first and export and import pst file via powershell, here are some detailed steps for your reference:

  1. Export the archive to a PST file

    New-MailboxExportRequest –Mailbox usermailbox -IsArchive -FilePath filesharePSTITarchive.pst

  2. Import the exported PST file into the mailbox

    New-MailboxImportRequest -Mailbox usermailbox -FilePath filesharePSTITarchive.pst

  3. Create a new and correct retention policy then apply this policy to the mailbox, wait for some time to make the policy take effect. Once the policy taken effect, all old messages which you want to move back to archive will be in archive mailbox.

For more details: New-MailboxExportRequest

In addition, here's a similar thread for your reference as well.

Joy Zhang
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  • Thank you Joy. What if the total size exceeds the mailbox size? Will the import fail? Or is there some grace space? This seems to be the case for at least one user, where the sum of mailbox and archive is 50,3GB, while mailbox size limit is 50GB. – Massimo Mar 03 '22 at 10:59
  • Based on my knowledge, the amount of mailbox storage available is determined by the mailbox type and the user's subscription license, you could refer to the blog to check how many storage for your archive mailbox. https://docs.microsoft.com/en-us/office365/servicedescriptions/exchange-online-service-description/exchange-online-limits#storage-limits It doesn't look like you've exceeded the mailbox size – Joy Zhang Mar 04 '22 at 05:53