SMTP, POP3 and IMAP (Email Protocols)

Email uses separate protocols for sending and receiving. SMTP (Simple Mail Transfer Protocol) sends mail from your app to your mail server and between mail servers, typically on port 587 (with STARTTLS) or 465 (TLS).

To read mail, clients use POP3 or IMAP. POP3 (port 995 with TLS) downloads messages to one device and usually removes them from the server. IMAP (port 993 with TLS) keeps messages on the server and syncs folders and read status across every device, which is why it is the usual choice today.