A colleague of mine is arguing that we should use an input mask for email fields. 

Personally I don't think it is necessary. For phone numbers I can understand since a phone number can be written in different ways. 

However everybody knows how to write an email address. Is it really useful to use a mask (and all the trouble it can get you with multiple devices)? Will people forget the @ if we don't provide the mask? I don't think so. 

If the user enters an invalid email address we already use inline error (on blur) so what is the point. What do you guys think?