Their apps are entirely lacking threading support, and IMO more egregiously, offline support.
Fastmail likes to brag about their JMAP protocol, and maybe JMAP is great and maybe it's not, but it's certainly the case that their iOS app is 100% nonfunctional when offline. I've been using various forms of email for quite a while. Microsoft's MAPI crud in all its incarnations works offline. POP3 works (albeit poorly) offline. IMAP works offline. Fastmail does not.
amluto|1 year ago
Fastmail likes to brag about their JMAP protocol, and maybe JMAP is great and maybe it's not, but it's certainly the case that their iOS app is 100% nonfunctional when offline. I've been using various forms of email for quite a while. Microsoft's MAPI crud in all its incarnations works offline. POP3 works (albeit poorly) offline. IMAP works offline. Fastmail does not.