@NeilSmithline You seem to underestimate the consequence of the problem. If you allow an address email as a username you could deny service to a company for a ton of users. For example, 2 companies provide a similar service. Company A doesn't want its users to switch to Company B. So, Company A, for every user they have, will create an account on company B using the email of their client as a username, Then when a user of A try to create an account for B, he will receive a message telling him that there is already an account even if he didn't created one. —
ꓨꓵꓷꓤꓯꓷꓯꓲꓠ 33 mins ago