Troubleshooting IMAP Migrations to Office 365

Everyone, just to inform you about a current issue on our side where you might have Skipped Items in your IMAP migration and when you click on Skip Items Details, you see nothing. This was reported previously in the blog comments by solmssen , thank you for raising this. 

This issue will be fixed in the future but for now use these commands to see the Missing Items that were Skipped. 

Connect to EXO PowerShell first, then run these 2 commands:
$SyncStats = Get-SyncRequest -Mailbox <affected user SMTP> | Get-SyncRequestStatistics -IncludeReport -DiagnosticInfo verbose 
$SyncStats.Report.MailboxVerification.MissingItemsInTargetBucket.DivergentItemsSamples | ft Kind, Subject, wellknownfoldertype, DateReceived

You can also export to CSV with a command similar to this:
$SyncStats.Report.MailboxVerification.MissingItemsInTargetBucket.DivergentItemsSamples | select Kind, Subject, DateReceived, wellknownfoldertype, FolderIdHex | export-csv -NoTypeInformation MissingItems_UserX.csv

There are 2 types of missing items: MissingFolderInTarget (missing folders) or MissingItemInTarget (missing individual items)

The items /folders were likely deleted from the target mailbox during migration causing these to be marked as Missing by the MRS. If you want to recopy these items, at least for now you will need to recreate migration batch / migration user for this user. 

Note: If you have missing folders scenario or even missing items and the WKFType shows None and these are User Created folders and name is not displayed, here are some steps to find out the folder name of the missing folder in Office 365 mailbox.
As always, you can open a support case with us to help you. I will leave these for now for the ones who want to do it independently: 

1) Retrieve the FolderIdHex from the Migration user statistics or Sync request statistics:

$stats.Report.MailboxVerification.MissingItemsInTargetBucket.DivergentItemsSamples | where {$_.Kind -match "MissingFolderInTarget"} | FL FolderIdHex

FolderIdHex : 563D313B503D494D41503B46503D33414444374239363132313032463241374442453445443446453838364530374538343743323444

2) Convert the Hex value (using Hex Editor in MFCMapi) and get the FolderPath (FP value below), in this case this is:

V=1;P=IMAP;FP=3ADD7B9612102F2A7DBE4ED4FE886E07E847C24D

3) Run the Get-ImapFolders.ps1 script from https://raw.githubusercontent.com/bradhugh/RandomScripts/master/src/Get-ImapFolders.ps1 on the Source IMAP Mailbox with the HashFolderNames switch:

.\Get-ImapFolders.ps1 -HashFolderNames

4) Check which Folder from Source Mailbox has the affected Folder Hash (3ADD7B9612102F2A7DBE4ED4FE886E07E847C24D in my case), what is the name?

5) The Folder with Folder Hash 3ADD7B9612102F2A7DBE4ED4FE886E07E847C24D is missing on the target mailbox.

6) We can double check this with Get-MailboxFolderStatistics <user> | FT folderpath in Exchange Online PowerShell for the affected cloud user, or run Get-ImapFolders.ps1 against the cloud user as well or IMAP Test https://testconnectivity.microsoft.com/tests/O365Imap/input which will list the IMAP folders (without hash).

Or if all these steps seem complicated, just compare the IMAP Folders list between Source and Target Mailboxes either with the GitHub script of Brad Hughes bradhugh  or Remote Connectivity Analyzer tool (tool also developed by Brad).