Sync Linked Mailboxes to Office 365

Brass Contributor

Dear all,


I have a very interesting situation with Office 365 hybrid migration. 


My client has 2 forests (with trust between them) with Exchange on Forest A.local Forest B.local has only accounts on it. Users on Forest A are regular mailbox users and most of them have been migrated to Office 365, and users on Forest B are linked mailboxes on Forest A and are disabled users but they can be seen and synced on Office 365 On office 365 the Linked Mailboxes are synced as 2 different users. 


Problem was: I was supposed to solve a problem with join both users identity in Office 365 to a single user which I managed to but Password was not working because it's in the Account Forest (B) and not syncing because the user in forest B is not the one synced to Office 365 but the Linked Mailbox on Forest A.   


Problem now is: After realizing that even when changing the disabled user's password on Forest A doesn't sync I decided to upgrade Dirsync but after the upgrade I got an alert that Dirsync stopped exporting changes to Office 365 due to the limited threshold of requested deletions which is by default 500 objects but in my case it reached up to 2250 users.  I checked the Dirsync users that are about to get deleted and found that all of them are Linkedmailboxes. Things I tried so far to sync the users: 


1- Tried Enabling the syncing of Disabled users by edit sync rules (Scoping filter)

UserAccountControl from Operator value = ISBITNOTSET =2 to ISNOTNULL = 0


2- Tried Changing 


In from AD – User Common from Exchange
of the Exchange forest



Expression >> SourceObjectType >>> IIF(IsPresent([msExchRecipientTypeDetails]), IIF([msExchRecipientTypeDetails]=2, NULL, “User”), “User”)


Changed to


IIF(IsPresent([msExchRecipientTypeDetails]), IIF([msExchRecipientTypeDetails]=666, NULL, “User”), “User”)


Prior to Upgrading Dirsync, I took a backup of all the rules that I have in Dirsync, I tried checking them but couldn't find where the rule that allows Linkedmailboxes to get synced and couldn't find it. I would be happy to share this and get help from anyone who did this before.Thank you


1 Reply

@Mohammed Hamada I have done a recovery from backup and it's all working well now.

Couldn't find out where is the culprit though.