Glossary · Protocols
IMAP lets mail apps read and organise email that stays on the server, so every device sees the same folders and read state.
With IMAP (RFC 9051), messages live on the server and apps sync a view of them. Reading on your phone marks the message read on your laptop; moving it to a folder moves it everywhere. Connections use TLS on port 993.
It replaced POP3 for most people because it suits several devices. Sending still goes through SMTP. Accounts with two-factor authentication usually connect IMAP apps with an app password.
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