Anonymous eventsignups (email only) should not contain the email of a known user.

Created by: marcoep

Pretty much as the title says.

Currently, its possible to have an eventsignup with a registered user with email x@y.ch AND at the same time a email-only eventsignup with the email x@y.ch.

This should not be allowed as AMIV members should be forced to use their useraccount for eventsignups instead of the anonymous signup functionality.

Any thoughts and ideas w.r.t. this?