You can also do it with cli .. modify the attribute 'zimbraPrefReplyIncludeOriginalText' for each cos that you want. This is how you do it.
$ su - zimbra
$ zmprov mc default zimbraPrefReplyIncludeOriginalText includeBody [this will set our thing]
$ zmprov gc default zimbraPrefReplyIncludeOriginalText [check if our value is set]
This should help you ..
