Outlook sucks as a POP and IMAP client because of the PST file format. PST is terrible, and prone to corruption. Without an Exchange backend, Outlook has to store *everything* in your PST. Calendars, ...
IMAP (short for Internet Message Access Protocol) is an internet protocol that lets you sync your email inbox across multiple devices. Most popular email apps, like Gmail and Outlook, use IMAP servers ...
Frankly, the world would be better off if they just abandoned the pretense and dropped IMAP support completely. I posted a while back on the topic of prospect of moving from Outlook+POP to ...