I totally get that SMv16 is well beyond schedule as there were a lot more changes required to do under the hood for a UIX overhaul, and I've got no complaints about that whatsoever. However I agree that we are in desperate need of a v15 release that fixes many of the major outstanding issues. I know personally we've been getting hammered by malformed emails that are taking all of our SM servers down for the count that was fixed in a custom build but not widely available for anyone who didn't open a Trouble Ticket for it. I was happy waiting a week or two for a final build but now that it is turning into over a month since the issue was first reported and supposedly resolved with a custom build my patience is beginning to wear a little thin as I can no longer wait for a fix while babysitting the SM Spool 24/7/365 on 5 servers. Honestly, my time would be far better spent at this point looking for an alternative to SM and migrating all our users.
SmarterTools feel free to take as long as you want with v16 but please get us a v15 Minor Release with the major outstanding issues resolved asap so that those of us who have been patient will continue to stick around rather than moving on to Kopano or Open-Xchange.