Help understanding the delay between AAD Sync and Recipient Object Showing up in O365

Question

We have ADFS and AAD Connect setup for authentication and directory synchronization between our AD and Azure.  I have a set of distribution lists and contacts that were created in Office 365 that I want to move to our on-prem Exchange / AD so I can manage most of the properties with the on-prem Exchange tools. 

I record the email addresses and other properties of the O365 recipient objects, delete the recipient object in O365, and recreate it on-prem without problem.  Once AAD Connect has run to sync the new object in AD up to O365 I can see it with get-msolgroup or get-msolcontact cmdlets, but the object doesn't show up in the Exchange Online part of Office 365 for what seems to be a highly variable amount of time.  It's varied between 33 minutes to almost 6 hours.  If I create a completely new object in my on-prem Exchange it shows up in Exchange Online within no more than 15 to 20 minutes of the last AAD Connect sync running. 

I suspect the extra delay for objects deleted from O365 and recreated on-prem has something to do with the overlap in display names and email addresses between the group or contact I deleted from O365 and the one created in the on-prem Exchange?  Any idea what's behind that extra delay, what my expectation should be when doing this move, and is there any I should keep in mind or work around to make migrating objects happen as quickly as possible?

Answer 1

Hi Matt,

Yes, your thoughts are completely correct. The main reason of the synchronization delay is that those display names and email addresses had been existing in the Office 365 online Azure Directory previously. Though you can delete them and they may seem to disappear at once, there may still be some cache in the back-end side of the Office 365 online Azure Directory. It may take some time for them to be utterly removed.

I have been searching for the relevant information for quite a while, however, there seems to be no Microsoft official resource talking about the exact time required to completely remove every bit of the data from the back-end side. According to my own experience, it mainly depends on the online server refreshing time, which we have no method to drive or accelerate at this point.

I’m sorry for any inconvenience this may cause. Thanks for your understanding.

Regards,

Allen