UPN sync changes $ to _

[Raechel Moermond]

So, I have a weird situation.  I have a customer that starts all their admin accounts with $ in the username and UPN.  We've noticed that when we sync these accounts to O365, the $ is changed to _, which is odd because most of the time when there's an invalid character in the UPN you get an error in Synchronization Service.

My question is - Is this expected behavior, changing the $ to _?  Personally, my recommendation is to remove the $ from the UPN and keep it for the domain\username, but considering the customer I would like to have more information first.

[#2]

@Raechel Moermond 

This is by design, see article

https://support.microsoft.com/en-us/help/2001616/a-user-s-office-365-email-address-unexpectedly-cont...

Even through dollar ($) is not explicitly on this list the list itself is not exhaustive and can be expected to extend to other special characters such as Pound (£) Hash (#) and Brackets ([]). I myself have experienced this with Dollar, Hash and Ampersand.

I would recommend what you said - remove these types of special characters completely and change them to something supported like ADM_username

Hope that answers your question

Best, Chris