Re: Dum question
Yes. Older Outlook clients have a crappy IMAP implementation, most people used POP email with them to stay sane. Many others just chose it as default.
That method of deleting email is only the _default_ for POP (vs. IMAP where the default is not to delete). You can have your POP email client do a variety of options for download & delete, or delete on a schedule, etc. etc depending on options you tick.