Email Protocols

The Simple Mail Transfer Protocol (SMTP) is a protocol used to send email. SMTP typically operates on port 25. For many years, Post Office Protocol version 3 (POP3) was the only means for retrieving email. POP3 operates on port 110. However, in recent years, POP3 has begun to be replaced by the Internet Message Access Protocol (IMAP), which operates on port 143. The main advantage of IMAP over POP3 is it allows the client to download only the email headers to the machine, so that the user can choose which messages are to be downloaded completely. This is particularly useful for smartphones and any wireless devices where bandwidth may be at a premium.

Each of these email protocols also has a secure version that is encrypted ...

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