Ok, I need some help confirming this, then figuring out a way to change it.
When one of my users clicks a "mailto:" link within the body of an e-mail address, I'm guessing one of the stock zimlets grabs that link and does something with it. If it's an existing contact, it will open a new message with that address in the "To:" field. If it's an address that the user has never seen, it instead attempts to create a new contact. First of all, does this sound accurate? Second, is there a way to change it so that when clicking a mailto link within ZCS, it always opens it as a new message, instead of attempting to add it as a contact?