[chrismorgan]

The main one I had in mind was POP3’s behaviour around deletion; my recollection is that if you don’t want it to work that way (and I think you might prefer not to in general, so you can be confident of having your own copy of everything), you run into practical performance, bandwidth and processing limits much sooner, because messages don’t have any external identity, so the receiver has to download everything every time to check if it’s seen it before. And you can’t just say “well only look at messages in this folder”—POP3 sees all, and that’s a problem.

But y’know what, I’m going to retract my comment for the case where you don’t want to keep a copy of anything. For most places, POP3 is generally unsuitable, but for this specific type of destructive server-to-server fetching, it’s reasonable.