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RolandK50's avatar
RolandK50
Copper Contributor
May 26, 2023

BUG ? exchange mailbox migration batch silently skipping mails when copying from source via imap

hello, i'm currently testing office365/exchange-online as we perhaps want to migrate from our legacy mail server to exchange online. i'm testing migration with the integrated migration solution...
Exchange Online
RolandK50's avatar
RolandK50
Copper Contributor

mderooijnope


source (shell on unix mailserver inside migration2 mailbox) :

[root@mail pve-devel.mdir]# find . -type f |wc -l
2699

thunderbird, source mailbox attached mailbox via imap:


target:
thunderbird, target mailbox attached via imap:

osx mail, target mailbox attached via imap:

 

PS C:\Windows\system32> Get-MigrationUserStatistics email address removed for privacy reasons -IncludeSkippedItems -IncludeReport

Identity Batch Status Items Synced Items Skipped
-------- ----- ------ ------------ -------------
email address removed for privacy reasons mymigrationbatch1 Synced 2695 0

 



4 Mails silently skipped / missing

this is reproducible. and making me nervous.  i have 70 accounts and more then 1,5mio mails to migrate...


RolandK50's avatar
RolandK50
Copper Contributor
May 31, 2023

so, apparently the problem is some deduplication feature.

apparently migrate batch is removing sort of duplicate elements


the problematic folder has mails from two differnt, but related mailing lists, where developers send emails to both sometimes - and these have been "deduplicated".

i'm curious though, why this happens - as this are different mails with different subjects

 

  • RolandK50's avatar
    RolandK50
    Copper Contributor
    Jun 01, 2023

    it seems mails getting deduplicated by included message-id - different subject line or content does not seem to matter.

     

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