We have been using Zimbra 8 FOSS since March 2013, and in that time there has been a few ideas and suggestions for Zimbra :-). I've not really had time to suggest these individually, so I'm doing them in one brain dump.
I would like to stress that these are my personal opinion from using Zimbra for the last few months, and are in no way intended to offend, or otherwise insult, mock or personally effect anybody.
- Zimbra should have an "Announcement" Mailing list for new releases, checking forums, and PM Portal is not always a viable option.
- Active Sessions should say something other than "Loading..." or be removed :-).
- Installing a renewed SSL Signed Certificate does not always work through GUI, and may need to be done via CLI, for me CLI is not a problem, for others it may be an issue.
- Zimbra should remember when a Zimlet is uninstalled. If you upgrade after uninstalling a default Zimlet, it will reinstall it.. (Disabling the Zimlet works around this issue)
- If you set MTA Trusted Networks to yo.ur.i.p/32 in a servers configuration, you can no longer edit server settings in the GUI, additionally, to set this IP option it is required to be set via CLI, this should be allowed, as sometimes a user may be using a dedicated server, and servers on other IP's cannot be trusted..
- Adding a built in backup system allowed on FOSS would be great. I know NE already can do this, but would be good for FOSS too.
- Add built in alternative spam scanning applications such as Pyzor or Razor.
Again these are just my personal opinion.