How to disable editing signatures by users?

[cr0n]

Is it possible to disable editing signatures by users? I would like to add individual, automatic signature based on Active Directory records (Setting automatic Default Signature - Zimbra :: Wiki)

and I need to make sure, that user cannot change his own signature from 'Preferences' tab in webmail.

(I don't want to disable entire 'Preferences tab' in COS).

[andre.netsol]

I would like to do that too! It is possible?