odd - I found that problem before I updated to 102.4.0 You could not drag and drop any contact to any address book or mailing list -''' IF''' you used the horizontal view. It did work in Vertical View. A bug report was created and was being sorted. I was sure it had been fixed because suddenly mine is now working. Note: if contact does not have a valid email address then it cannot be put into any 'Mailing List' anyway for very obvious reasons. But in my version of 102.4.0: I can select address book and drag a selected contact from that 'address book' into another 'address book' - but it does 'move' the contact. I can select eg: 'personal address book' and drag contact from that 'personal address book' into a 'Mailing List' providing that mailing list is a subgroup to the 'personal address book' which contains the contact. So basically drag contact over to the left pane, hover over mailing list and release to drop. It is not possible to drag and drop any contact from eg: 'Personal Address Book' and try to drop them into a Mailing List that is a sub to another address book. Contact must be in the associated address book before it can be added to a sub group/mailing list.