Brian,
The goal is not to flame but limit folks who just come to ask and ask and ask without helping us help you. There are 100's of posts here each day and we read them all. A large % of them never offer enough information about the problem they see. So after we get enough info or multiple folks report the same issue we ask that the community files the bug. For paying customer and network trial folks we file the bugs on your behalf if you wish. For that service though you need to use the support system. Just so we can track the request and tie it to your customer information. Here in the forums it's more of a free for all. We have a mix of customers, prospects, tire kickers, and flamers. So the SLA (if you can call it that) is a bit looser. While we don't want to discourage your use of the forums your posts/request for info need to be a little tighter framed. So error on the side of too much information and help us understand what you've tried and what you are getting for errors etc.
So sorry if my 'file a bug' was taken as hostile but my quick read of your "me-too" post was that you can confirm the problem as stated so IMHO it was ready to be filed in the bugzilla.
WRT our support team they do their best to get back to folks ASAP. Taking a quick look at your most recent request doesn't seem like a super high-priority/urgent item so I'm sure other more critical issues were handled before it. Obviously if you had a critical P1 service affecting issue you'd want that prioritized above a question or minor defect.
As you said let's get back to the problem at hand.....
As John pointed out there is a related bug filed:
http://bugzilla.zimbra.com/show_bug.cgi?id=6531
This bug will address the report not arriving to some folks when mailx is not installed. The intermittent issue is something relatively new with 3.1.1 and at this time we don't have enough info to reproduce it in house. ie it's not happening on our internal systems. If you or anyone else can help figure out what the exact cause is that would be helpful. Seems rdavisids is on the right track.