I'll admit that parsing BODYSTRUCTUREs is non-trivial at best, but POP has nothing of the sort. Okay; I think you can get just the headers of the message, or just the first n bytes, but nothing intelligent.

POP isn't an attempt to solve the problem (of remote mailstore access). IMAP is a flawed attempt to solve the problem. This means that IMAP is more deserving of criticism.

It's not exactly hard to send the same search to multiple folders, and POP doesn't even have the concept of multiple folders.

It's not hard, but it shouldn't be the client's job. There's a lot of protocol baggage associated with SELECTing each folder in turn (you can only search the currently-selected folder), whereas the server has all the information to do it all in one go.

I'd say that changing a message's title is beyond the scope of any mail client. However, you could rewrite the message and push it back to the IMAP server, which I'm pretty sure you can't do with POP.

You can't rewrite it exactly the same IIRC (you can't set the envelope). But semantically, you don't want to rewrite the message, you want to annotate it. You can associate binary flags with the message (if the server supports it) but not text. Acorn's !Email let you change the title that appeared in message lists (when you opened the message you saw its original title).

Peter