alt Hacker NewsA big +1 for fastmail, but their official ios app is 0/10 the last time I used it. Not a big problem if you use mail.app or their website on desktop.
Something I've done and which has been a big quality of life improvement is to set up a folder with 30 day retention, then an email rule to move any emails with `+` or apple relay there. Those are legitimate emails I want to read such as online order status, but I don't need them in my every day email.
Their ios app works ok for me. But I really wish it was fully native, and not just a webview wrapper of their webmail client. They have truly excellent IMAP support though (and JMAP too). So yeah, mail.app works great.
They also support apple's custom XAPPLEPUSH IMAP extension, which means fastmail supports mobile push over IMAP. I think they're the only ones who support it other than apple.