The implementation in the SQL driver sub-optimal as it uses the same member format and internal API as the Kolab driver.
We might need to improve this.
Requires https://github.com/roundcube/roundcubemail/commit/b206cbc87a2f766dfc8150a4fdf29531e0782e27 and https://github.com/roundcube/roundcubemail/commit/a34f7160511e87bff64254fbafb7d10de8e0f59d