Would just like to say this works quite well! I have just tried it out.
You have to go to the homepage of the WebCompose Author as opposed to downloading from the Firefox extensions page if you use Firefox 1.5+.
After that, entering my details in the Preferences on the Extensions window in Firefox I added my Zimbra server addresss in the other section like this:
Rudimentary I know but it kind of works!
Now, how would I get it to accept my username and password without it forcing me to log in to Zimbra first?
Also, If you are logged in then clicking on a mail ink on a webpage opens a seperate Firefox window from the main Zimbra window (already open and logged in) and shows the To: address correctly.
How could I get Zimbra to read this as a request to open the compose page in the existing window as it woudl normally do if you clicked to compose within Zimbra?
This will be a great feature if it works properly and would be another complaint from our many Outlook users out of the way!