Zimbra Desktop Client seems to have a problem with window size. I didn't see anything in Bugzilla.
From my requester---------
My test was performed on Mac OS X 10.5.5
1. Opened app
2. Zoomed to full screen
3. resized window to about have screen
4. re-zoomed to full and back a few times
5. quit the app with it zoomed to full screen
6. re-launched app and it opens in full screen
7. zooming window results in tiny window in upper left
8. resize to half screen and do the zoom back and forth a couple times
9. quit while zoomed to half screen size window
10. launch app, and I get half screen window...
11. hitting zoom button now gives me full screen
Seems like it forgets what the non-full screen zoom level is if you close the app when you're zoomed to full screen.