O365 Distribution lists

[Srinivas Nyayapati]

Can we modify the existing Distribution Lists post migration to O365 ?

[#2]

It depends on where the Distribution lists reside if it's on-premises managed distribution list you can modify the DL as you usually do and then the changes will be synced up, like new members, to the cloud, assuming you have Azure AD Connect in place.  You can also create and manage, cloud based, distribution lists directly in Office 365.

Alternatively, recreating the on-premise based Distribution lists in the cloud has some benefits and then they can easily be upgraded to Office 365 Groups at a later point if they qualify.  There are some scripts that can help with this process.

[#3]

Thank you for the detailed response !.
I tried to modify the DL and it is showing the below error :
The action 'Update-DistributionGroupMember', 'Identity,Members', can't be performed on the object 'xxxxxx' because the object is being synchronized from your on-premises organization. This action should be performed on the object in your on-premises organization.

[#4]

That message means you have to modify the distribution list using your on-premise management tools and not in the Office 365 admin portal.

If you have access to the 'Active Directory Users and Computers' program, you should be able to find the Distribution list and modify the membership accordingly.  Subsequently, those changes will be reflected in Office 365, once they get synced up to the cloud with Azure AD Connect, which by default will happen within around 30 minutes.

[#5]

"if they qualify" is the key phrase here.  There are so many conditions for ineligibility that upgrading isn't that straightfoward yet.  Hopefully Microsoft is still working on improving this.

[#6]

"easily be upgraded"?  Hmmm... Not so. https://www.petri.com/convert-dl-office-365-groups 

The issue here is ownership. An Exchange object exists on-premises (always with that last "s") or in the cloud. You can only manage an object on the platform where it is owned. Therefore, if a DL is an on-premises object, you can only manage it with the on-premises version of the Exchange Admin Center (EAC) or PowerShell. 

There is no good way to transfer a DL from on-premises to cloud apart from deleting it on-premises and recreating it in the cloud. When the DL is in the cloud, you can then consider moving it to an Office 365 Group, providing that you meet all the requirements.