Method to check if e-mail address is indifferently used in users, groups or aliases

[ilclaudio]

Using this library I have to use different methods to retrieve Users, Groups, or Aliases.
Is this right or am I wrong?
But if I have an e-mail address and I'd like to know if it is used in one of these entities I have to check all of them one at a time.
Is there a method that checks if an email address is used anywhere?
I think that it would be useful.

Thank you

Claudio b.