What is the 'Internet Message Access Protocol' (IMAP) and what is the key operational difference between IMAP and POP3 from an end-user perspective?

• A.IMAP downloads and deletes email from the server; POP3 synchronizes across all devices
• B.IMAP (TCP 143, IMAPS TCP 993) maintains email on the server and synchronizes folder state across multiple clients; changes made on one device (read/delete/move) are reflected on all others. POP3 (TCP 110, POP3S TCP 995) downloads email to the local client and typically deletes it from the server; best for single-device access where server storage is limited
• C.IMAP uses UDP for faster email synchronization; POP3 uses TCP for reliability
• D.POP3 is the modern protocol; IMAP is deprecated and should not be used