Check for failure on setting the Mail

[VincentWo]

The return value of ldap_mod_replace is not checked when setting the Mail. Would be nice to check for that and to throw an exception in case of failure.

This is not only a theoretical concern: I am currently trying to enforce unique E-Mails through LDAP and setting a non-unique one just silently fails at the moment.

[blizzz]

That won't be enough. Currently, the server code sets the email address (if allowed) in the database, then emits an Event that it was changed. A cancellable Pre-Event is required. Could you open an issue on the server repo? Likely we meet there again :)