Just a few niggles with possible suggestions here and there.
1) IMHO using an acronym like GAL is counter productive to new users.

2) The whole concept of Distribution Lists is fubar, but I can adapt to the system. Why anyone would want to have a "distribution list" that is an email address that filters down to users is very bizarre. Back in the day we called these things mailing lists. Great for spammers. My definition of a Distribution List looks more like a Zimbra "Contact Group". Which I'm glad to see is being addressed although it still feels clunky. For example there's no easy way to easily select a Contact Group in the New Mail dialog. You'd have to know the name of the group which a new user may not, particularly in a corporate setting. There's actually no acknowldegement at all that Contact Groups exist when creating a new message. Now this could be a result of the RC1 status so if this is being looked at I apologize. But there is clearly a good deal of work left in the "Contact Group" area....What about Global Contact Groups? Another must have feature. In a company that relies heavily on Contact Groups it doesn't make sense to have to create the same contact groups under each users profile.

3) Nice addition of the html only "basic" client. Will be an excellent alternative over a slow link or when running on a sub-par machine. A niggle here again with the contacts. You should be able to select a contact and have an action button for compose email which would populate a new compose window with the selected contacts. Just seems odd the way Zimbra has problems handling groups. It's almost like the devs have tunnel vision with the concept. Also When in compose mode the Find feature does not find Contact Groups, even though they are listed in Contacts. (This is all in the html client.)

Zimbra is extremely good and will likely be the next email system for our corporation, but these problems with the contact groups, composing sending and managing of them must be addressed before we can even think of deployment.

Regards and hope these issues will make it into 4.5