Support plus-addressing in emails, which is invaluable for testing
We need to create many users for our testing environments. Normally, the way we do this is to use 'plus-addressing'. This is a convention by which you can add a '+' sign and then anything afterwards to an email address, and it gets delivered to the recipient as if the + and everything after did not exist i.e. the following two email addresses are different but get delivered to the same place:
This is a standard called 'sub-addressing' which is supported by quite a few mail providers, including Google Gmail, Google Apps, Yahoo! Mail, Outlook.com, and quite a few others. See https://en.wikipedia.org/wiki/Email_address#Subaddressing.
This is extremely useful for testing, because we can create multiple accounts in AAD which all map back to the same physical address. These multiple accounts are necessary to test things when developing an application that uses AAD, like accessing the system as different users that have different permissions, client associations, and so forth. Without this, we have to create fake addresses at our email provider, and alias these to real addresses manually, which is error-prone and time consuming.
Currently when I try to create a plus-address via the Microsoft Graph create user API (POST https://graph.microsoft.com/v1.0/users) OR invite API, I get this error message:
com.microsoft.graph.http.GraphServiceException: Error code: Request_BadRequest
Error message: Property userPrincipalName is invalid.
Please support plus-addressing, which is a very common way to deal with this kind of situation. If you like, make it an application option that is off by default, but that can be enabled by admins for specific applications.