What is the Difference between the Mail protocols: IMAP, SMTP and POP3?




In a nutshell…

IMAP: Mail stays on server, accessed remotely, normally needs to be deleted manually.

POP3: “Store and Forward” technology, stays on POP3 server until downloaded to client program, then normally auto-deleted from server (although the client can be configured not to delete after download)

SMTP: Primarily for communication between mail servers, real time as opposed to store and forward. Client normally sends direct to SMTP server (because it is live) as opposed to receiving from a POP3 server (on demand) where mail has been “stored”.