Why did you remove alias/forward page? it was handy to give a user alias capability but disable forwarding for that domain if we dont want them to be able to forward their emails.
The removal was an attempt to make things easier to understand.
There are still possibilities to patch qmailadmin to not allow remote forwarding...
Also, is it possible to disable user to set forwarding from qmailadmin when he/she enters to change his password?
Not at this point, but it could be a future feature of qmailadmin (filing an RFE on the sourceforge project page would be a good idea: http://www.sf.net/projects/qmailadmin)
Jeff
