I too have had some issues with support. I am very new to SM. I haven't even gone live with my hosted SmaterMail deployment and I'm frankly hesitant to, because of some issues I have had and how much of a "back seat" approach support takes. I put 20+ hours into this project and I would like to not have it go to waste.
I shot off an email to Emily saying how disappointing my support experiences were and I wanted those issues resolved that business day. That was the 15th, it is now the 25th and not all of the issues are resolved. Granted the new tech has done a good job, but two main issues get glossed over and I keep bringing them back up and they want another ticket. Just fix the bloody issue. It also just seems inefficient and slow to resolve tickets. A simple phone-call and 30 minutes would have probably fixed the issues.
Honestly, two things really need to happen for me to stay.
1.) The documentation needs a MASSIVE overhaul, a lot of it is out of date and most of it isn't intuitive.
2.) support needs to be significantly more hands-on and more involved.
The bugs and the unfinished parts are purely just annoyances. I understand the MAPI project was a massive undertaking which probably sucked up a lot of resources, but as a business person when my human resources are stretched thin I hire contractors. Their D&B listing looks a bit off but so does mine, but the ballpark-revenue/workforce ratio is a bit awkward. Unless D&B is way off (it can be). But lets for sake of argument assume revenue is light compared to the human capital liabilities.
SM is very inexpensive and I mean that is a great thing. But, aside from the $300/incident emergency response, I have budget for a "Premium Support" package. Lets say telephone call back with an SLA. So low priority would be 24 business hours, medium priority would be 8 business hours, High would be 4 and critical would be 2. After hours and emergency within an hour can stay the $300. Probably some "Professional Services" would work also, at $150/hr. I can say "Hey, I authorize 4 hours, make x work." That would generate revenue to hire resources for the programming side. Could that be something that could be done for up to $0.50/user/month? I would also charge $5 per critical ticket. I do, it's a GREAT motivator that stops those customers that make EVERY ticket critical. Now only truly critical tickets get marked as such and all for just $5.
The other thing would also be have a single dedicated RSAA. I set you guys up with a Connectwise Control account (with 2fa) with access to my two mail servers and usernames/passwords for both. I do it once, and don't have to redo it every single time. Even if it is once a year, that is better than every ticket. If you want to charge for that, I'd pay $5/month for that. Technically, even at $120/year or a $250/lifetime I would grudgingly pay that. (hint: I like the $5 one better).
I understand some people might not have my budget. That's why you can keep your current pricing and add-on features. The only thing would be, where a lot of companies make mistakes, over-pricing the addons. Making premium support $1+/user/month would kill it. Let's put it this way, any chump with 500 users can get Office 365 with hands on support through a vendor for $3.28/user/month for Exchange online plan 1. If you take into account that you are not O365 and the need to host said mail server and it doesn't have active/active load balancing and failover over WAN without the need for shared storage. You want to stay at the very most $2/user/month. Put those costs into a calculation. Let's say $150/month for the hosting costs and SPLA Windows License. At 250 users that would be $0.60/user/month, plus $0.70/user/month for SM. That's $1.30/user/month. So you have $0.70/user/month for up-sells and addons. I would say $0.30 - $0.40/user/month is more than reasonable. Just resist the urge to go, "Oh, thats $6,489.99/year" like most do. At that point, I'd eat the profit reduction and move them all to O365 and call it day and go get a margarita.