Postbox is pretty good, and would have been the solution to my mail client woes, except that:

* even after you've paid for the product, the only way to get support is to pay $10 for every question you want to ask, however basic or advanced it is - and you'll need support, because...

* there's erratic unpredictable behaviour at many places; is it some subtle bug in the software? or is it some weird about:config option that you have to set to get things working as expected? Who knows! If you're lucky, you'll find a solution in the Thunderbird forums that works. Often though, that dialog option has been removed from Postbox or that about:config option no longer does anything, and...

* the documentation is no help. It's no worse than the average startup's help pages, except in this case, as mentioned above, there's no support - so you'd expect that to be compensated with exhaustive documentation, but no such luck. The docs cover just the most basic cases and leave all the complex interactions of emailing to your own guesswork. Also...

* the devs avoid users like the plague. The only-paid-support thing is (explicitly stated as) a consequence of this, but this even extends to bug reports and feature requests - which are free of cost to submit, but the two bug reports (and one or two feature reqs) I submitted were met with only gaping silence. The interaction on Facebook and Twitter too seems limited to version announcements and rare one sentence replies.

I really wanted to like Postbox, for it to be the solution, because it was quite a good product with advanced capabilities and a quite reasonable cost. But it didn't seem like a reliable option for the long run given these limitations.

> the devs avoid users like the plague

A recipe for a terrible product. I tried Postbox when it came out and found it to be unbearably buggy (like they had released an alpha version). I couldn't even get Gmail to work, which should have been user story #1 for them: set up Gmail account.

Now I understand the culture that made it such a piece of garbage and will continue to avoid it like the plague.

Interesting, I'll definitely take a look at this. I don't mind paying for it, but I'd be a bit iffy on going from a nice open source solution to a proprietary one.

EDIT: Nevermind, no Linux build, that's out for me unfortunately.

"4 GB of RAM (8 GB recommended)" Wow why does it need so much RAM.

Interesting story tangentially related to this question. I just finished building my new gaming rig - the only thing left is a GPU which should be coming in the mail pretty soon. The CPU I have, a core i7 4790K, has a pretty decent GPU so I was testing it out the last couple of days. The first game I tried was GTA 5. It ran smoothly (albeit at the lowest possible settings and 720p resolution). I was pretty impressed with the integrated graphics' performance. Yesterday I tried GTAV out again for a little bit and I observed that it was ... way too choppy and basically unplayable. I couldn't figure out the reason why. Then I saw that Thunderbird was the only application that was open aside from Steam and GTAV. I closed it down again and boom, back to consistently high framerates.

What is the catch here? Granted I'm using the integrated graphics that came with the CPU but I have 32 GBs of RAM. What gives!??

How long was Thunderbird open before this happened? It could have been a memory leak, which can be really expensive when working with web-rendering software.

It was open for a bit. This experience has made me start to question all those times I had slow-ish response times and Thunderbird was open. Slowness or game choppiness should be unacceptable given that I have a 4.0 Ghz CPU and 32 GB RAM. I guess it is time to look for a new email client :/

Not sure, but it's currently using just over 200 MB of RAM here (on Windows 10).

Additionally, the Postbox search feature is way better than Thunderbird's.