Service-specific Mail Adresses
Users might want to select different mail addresses for RocketChat and e.g. Gitlab (and also password reset). This goes beyond #62 (closed).
Users should be able to add multiple (verified!) mail addresses to their account. They should be able to select a default mail address and overwrite the default for specific services.
We don't have this flexibility with LDAP, so this is a v2.x.x feature.