I'm generally content with fastmail, but the webmail would need some polish. (and by polish I do not mean the user hostile react rewrites MS and Google are pushing)
- Hungarian translation is not the best (they provide it, thus I use it). It has missing parts, and sometimes problematic mistranslations. Localization (date format and date conventions) is sometimes incorrect in the calendar.
- Some calendar workflows are clunky and unintuitive.
- some other similar UX papercuts (don't get me wrong, others have theirs too, but it would be nice if fastmail would be better).
- The most annoying: if I'm logged in I need to open a private browser session to see their main site, as it instantly redirects me to the app, and I cannot access resource from within.