If you're looking for a more traditional email client, I'd recommend MailMate[1]. It's a no-fuss email client designed for power user (GPG support, Markdown support, advanced filtering, text-only mode, etc.) I've been using it for half a year with Fastmail (personal) and Gmail (work) and pretty happy with it.<p>The author also maintains a blog[2] where he post quirks about several IMAP implementations. For example, Yahoo IMAP[3] or Gmail labels[4]. The app itself also handled all these edge cases very well.<p>[1]: <a href="https://freron.com" rel="nofollow">https://freron.com</a><p>[2]: <a href="https://blog.freron.com" rel="nofollow">https://blog.freron.com</a><p>[3]: <a href="https://blog.freron.com/2017/slow-descent-into-madness-yahoo-imap/" rel="nofollow">https://blog.freron.com/2017/slow-descent-into-madness-yahoo...</a><p>[4]: <a href="https://blog.freron.com/2013/mavericks-gmail-apple-mail-and-mailmate/" rel="nofollow">https://blog.freron.com/2013/mavericks-gmail-apple-mail-and-...</a>
I'm partial to Airmail (<a href="http://airmailapp.com/" rel="nofollow">http://airmailapp.com/</a>), which I use for a mix of Gmail and self-hosted (IMAP) addresses. Works great, lightning-fast to use, and with a very Mac-native feel.
I've really been enjoying Astro recently (<a href="https://www.astro.ai/" rel="nofollow">https://www.astro.ai/</a>). I was a big Newton/Cloudmagic fan before they shut down in the last month, but nearly everything I liked from Newton is also present in Astro. Unified inbox, snooze/send later, excellent keyboard support, etc.<p>Also has the best "less important emails" inbox implementation that I've used so far. The whole gimmick of an AI bot I could chat with is just that, a gimmick, but bot the desktop and mobile apps are solid.<p>Wishlist items remaining: Newton had you have a Newton account that would automatically set up all your accounts when you installed it on a new device, but Astro doesn't do that. Also, I'd love it to automatically pick the right account to send from once I type in the recipient's address, based on past correspondence, like Newton did. But neither of these are even small issues.
If you are looking for an email powerhouse that requires some time to set it up in order to use its full potential, then I recommend to take a look at MailMate: <a href="https://freron.com/" rel="nofollow">https://freron.com/</a>
I've had a good experience with Mailspring. It has a clean user interface and sets of key bindings that are similar to email clients like Mail.app, Gmail, and Inbox.
I’ve been using Boxy (<a href="https://boxyapp.co" rel="nofollow">https://boxyapp.co</a>) for inbox for a long time and now they’re on to making Boxy Suite (<a href="https://www.boxysuite.com/" rel="nofollow">https://www.boxysuite.com/</a>) which should cover Gmail and Calendar once Inbox is deprecated.<p>Overall quite happy with them.
I love <a href="https://www.uniboxapp.com/" rel="nofollow">https://www.uniboxapp.com/</a>, mainly for the way it treats mail as a continuing conversation like iMessage. It hasn't been updated in a while, but works well. I can't go back to the dreaded thread layout of most mail clients at this point.
I've been really enjoying Canary. Good cross platform support for iOS and Mac and its a one time purchase instead of monthly. Add in the security features, snoozing, and smart notifications and its almost at inbox levels.