Using tags in mail-workflow

[simplyfat]

hi,
i know two small businesses which use zimbra's tagging-ability in their email handling workflow. they have tags like:
- done
- in progress
- todo
- todo urgent

the problem is, that you cannot easily switch the tag assigned to an email; you have to first remove the old one and then add the new one (because otherwise you see the "rainbow-tag")

is it possible to make the tagging-feature more flexible? i'm thinking of something like a checkbox "remove other tags on assign" or even better a list of other tags which should be removed when a certain tag is added to an email.

what do you think of such a feature?