I have run into something for which I am not able to find a solution.
When an External user is given access to a SharePoint site it creates a #EXT# user in the active users list.
I create contacts in my Active Directory and Synchronize them to Office 365 which works absolutely fine. The contacts are not part of the organization but are external users. The same external users are then given access to a SharePoint site which creates a #EXT# account. This does not cause any issues with Synchronization as the contacts were synced before the #EXT# accounts were created.
However, in the second scenario I give SharePoint access to external users first and then try to sync contacts to my active directory which have the same email address. DirSync recognizes a conflict and does not allow me to synchronize the contacts since the SMTP address is the same.
Would deleting the SMTP address of the #EXT# account take away the users access to the SharePoint site. Also, the number of external users who are given access to SharePoint sites is huge and hence monitoring whether a #EXT# account is created for a particular contact before syncing is practically not feasible.
Please help find a way out.