I have an Office 365 tenant with Azure AD Connect synchronization and want to add the Exchange extensional attributes to the AD schema, to use additional features (like hide distribution list from global address book).
To do this, I think we have two options:
1. use Exchange setup to install all Exchange AD attributes
2. manually add the MS-Exch-Extension-Attribute (1-15)
After that I can select only the required attributes to be synchronized to Office 365. I am aware of, that extending the AD schema is a task that has to be well investigated to avoid the tenant from getting stopped running.
Therefore I am looking for hints to extend the AD schema without interrupting the mail flow and other things related to Office 365. Do you have any experience in extending the AD schema for an environment already connected to Office 365?