It is our policy to upgrade Zimbra to the latest version promptly after testing.  And what, exactly, is our testing procedure?  Our testing revolves around our sandbox servers, a testbed simulating our Zimbra cloud environment, and involves much of our team.

1. Upgrade the sandbox - Systems Administion
   
2. Administrative testing - Systems Engineering
   
3. Client-side testing - Support Specialists
   
4. Issue review and go/no-go decision - Operations Manager
   

Issues, when/if found, are listed in our public blog and private news about the planned upgrade.  Even after the decision to move forward, the decision can be reversed all the way up to the actual night of the installation by engineering for a variety of reasons, including just for one example, failure of full-backups to complete as expected. 

The issues we check during our client-side testing are listed below.  Caveat: while we make commercially reasonable efforts to test these and other features prior to upgrade, there may be bugs, even ones impacting the features we test, we cannot catch until after an upgrade.  This is one reason we don't upgrade immediately when updates are available, instead wait to identify most issues in advance by the community, and by our own testing.

We welcome your comments and suggestions to improve this table of Zimbra client-side features tests.  Please note that we cannot test every feature, must therefore prioritize carefully, while our Operations Manager reviews every suggestion for features to test, we can only add select features to the list.

Features	Web client (Advanced)	Web client (Standard)	Zimbra Desktop	Outlook	iCal	Blackberry (BES)	iPhone	Windows Mobile
Send internal email					n/a			Will
Send external email					n/a			be
Spell check		n/a	n/a	n/a	n/a	n/a	n/a	tested
GAL populating (3 addresses / groups)				n/a	n/a	n/a	n/a	as of
Drafts saving				n/a	n/a	n/a	n/a	5.0.19
Filter rules
incoming mail change folder					n/a	n/a	n/a	n/a
incoming mail add tag					n/a	n/a	n/a	n/a
outbound mail				n/a	n/a	n/a	n/a	n/a
Calendar Events
add event
delete event
modify event
send appointment verify delivery
sync event
Free/busy populating						n/a	n/a
Accept/decline/tentative buttons active
Shares
share a folder		n/a			n/a	n/a	n/a
share an address book		n/a			n/a	n/a	n/a
share a calendar		n/a			n/a	n/a	n/a
share a task list		n/a			n/a	n/a	n/a
share a briefcase		n/a		n/a	n/a	n/a	n/a
HTML Signatures		n/a			n/a	n/a	n/a
Out of office reply		n/a		n/a	n/a	n/a	n/a
Downloads (1 MB, 20 MB, 50 MB)	Will	be	tested	as of	5.0.19
Uploads (1 MB, 20 MB, 50 MB)	Will	be	tested	as of	5.0.19
Attachments (1 MB, 20 MB, 50 MB)	Will	be	tested	as of	5.0.19