Thanks for the link, I added my vote to it. Also found the rfe for setting 'request read receipt' as default:
Bug 39386: read receipts default behavior per COS
Basic settings that I wish had been already implemented by version 6 of Zimbra. Would have saved me from some unnecessary aggravation from end users not happy with the switchover from Outlook.
As for persisting the panels layout/sizing, I hope Zimbra Desktop will take care of that issue, and perhaps these others as well -- though I have yet to test it.