I'm still trying to catch up to my user's requests for all sorts of functionality... One that came in last month was the ability to add a "hot link" to a message when composing. I've tested myself and found that when I select HTML mode, I can copy and paste HTML text from another web document and it will carry the "hot links" with it. But there doesn't appear to be a way to edit them or view them in raw HTML.
Specifically I have users who want to be able to not just post a URL in a message and have it work as a clickable link, but they want to be able to obscure the link behind message text like this. This is something they used to be able to do in our old iPlanet system. At the moment, it looks like in ZCS 4.5.10 the best I can offer them is to locate a web page with the link they want somewhere on it and then highlight and copy the text, then paste it into the compose field with Ctrl-v.
Any suggestions beyond that? It looks like Zimbra really should be able to do more given the document-centric nature of Zimbra overall.