None of them have good (or any) support for managesieve.
Without managesieve (or some other autotagging mechanism), email is just a big pile of junk.
Even Gmail doesn't support editing filters on the mobile app. It's ludicrous in 2026. And their filters are strictly weaker than Sieve.
None of them have a feature to "quickly generate a filter rule from a message".
None of them have a way to generate a forum-like interface from a mailing list more or less automatically.
None of them (except deltachat, I think), support displaying messages linearly, one below another, rather than one at a time.
One at a time is also important. When I'm writing to my boss, I am writing a message as if it is a document. But when I'm writing to my girlfriend, I often want it to a be a one-line response.
Overquotting is badly managed. Gmail hides the previous message under a button, which is super slow, but most of the time overquotting is not even needed. There should be a button to "not quote" and "strip quotes automatically".
Without managesieve (or some other autotagging mechanism), email is just a big pile of junk.
Even Gmail doesn't support editing filters on the mobile app. It's ludicrous in 2026. And their filters are strictly weaker than Sieve.
None of them have a feature to "quickly generate a filter rule from a message".
None of them have a way to generate a forum-like interface from a mailing list more or less automatically.
None of them (except deltachat, I think), support displaying messages linearly, one below another, rather than one at a time.
One at a time is also important. When I'm writing to my boss, I am writing a message as if it is a document. But when I'm writing to my girlfriend, I often want it to a be a one-line response.
Overquotting is badly managed. Gmail hides the previous message under a button, which is super slow, but most of the time overquotting is not even needed. There should be a button to "not quote" and "strip quotes automatically".