These changes complement #11 where locally saved e-mail address can be "name.surname@example.com", but e-mail address in LDAP can be "Name.Surname@example.com". They are treated as two different e-mail addresses and user gets 2 invitation notification e-mails. We change ThreePid model's address property to convert all info to lowercase and [be915ae](be915aed94) can do it's job better.
The downside of this is that all medium addresses get converted to lowercase, not only e-mails. For now I can't think of any examples where medium values need to stay case sensitive.
