Um what? Nothing in IMAP prevents you from doing the same. Just because most client implementations assume you want to keep your mail on the server by default, does not mean the protocol doesn’t account for the other possibility.

And to be fair, configuring most clients to retrieve and then delete, or keep a local copy in addition to the server one, is not difficult at all - these options are not hidden or anything.

I would challenge you to show how you would configure a common IMAP client to keep email locally and delete it from the server.

imapsync for example or drag'n'drop/filter in Thunderbird. Not that difficult.

POP3 is exceedingly simple protocol compared to IMAP. I'd rather use the simplest tool for the job.

In case the password leaks, attacker can only fetch new messages over POP3, and not plant them or fetch the entire archive from the server. (yeah, I can fetch and delete over IMAP too, but then what's the point of all the extra unused complexity of IMAP, it's just an extra risk)

JMAP works great for this too. It’s a shame JMAP isn’t widely implemented - it’s a lovely standard.

So does IMAP? Most clients only cache headers because it’s faster and most devices are always-connected; but you can certainly locally download the entirety of your IMAP contents.

Considering you have to download the entirety of the mail contents to read it anyways, I have no idea what makes you think this is an impossibility.

Yeah, but typically the difference is that you can't see IMAP as a backup. Whereas with POP3 (and not having your client set up to automatically delete emails on the server) you can.

With IMAP, when an email gets deleted by some client, other clients will also delete their local copies of that email. That won't happen with POP3.

But I haven't read either of the two protocols, so I'm not sure whether that's something required by the protocol or just a common behavior of clients.

> With IMAP, when an email gets deleted by some client, other clients will also delete their local copies of that email. That won't happen with POP3.

This is not an IMAP feature, this is a client feature. There are plenty of clients that don’t sync deletes, if you don’t want to.

Or, just don’t delete your emails? If you delete a POP email from your client, it’s also gone for good.

Yeah, it's much better with POP3, when one client downloads everything it deletes it from the server /s

This isn't IMAP limitation, this is how clients implemented it. Nothing stops one to download every message over IMAP and never delete them.

Common POP I implementations let me leave things on the server indefinitely, for a chosen period, or to delete immediately on retrieval, leaving the local copy intact. Can you think of any IMAP implementations that allow that?