And decent spam blocking. I switched to Gmail after 10 years with Yahoo because I was fed up with 15 spams a day in the inbox.

> conversation threading

I believe this existed before gmail

> gigabyte storage

was not a tech problem before

> speed

in what way? the ui was and still is as fast as most lightweight desktop clients

> powerful search

maybe, although some clients supported powerful search with regex before

I think gmail was not that innovative, but it did bring everything together very well, in a very user-friendly way, along with some new-ish stuff like tags and the no need to delete anything.

Actually - when was conversation threading introduced in GMail? I know the Apple's Mail.app had it in 2011.

It was part of the initial launch in 2004.

for me: what is that "a lot more"? I just want to learn something new (btw, labels/tags are not really new, just redesigned imap folders)

Tags have an important difference from folders in that messages can have multiple tags and you don't think of messages as being in a folder.

Personally I find this quite useful and it definitely improved the way I use email.

Opera Mail had tags quite early on, not sure if it was before Gmail though.

Non trivial statistical analysis of email contents and your interactions with your email to effect decent prioritisation?

That would be my top feature in gmail.

s/gmail/mutt/

FTFY