Dictionary · Protocols and Ports
IMAP
IMAP — Internet Message Access Protocol
Email · Beginner
A mailbox protocol that leaves messages on the server so multiple clients can see the same folders. The traditional port is 143, and the encrypted form commonly uses 993.
Your phone and laptop can both see the same mailbox because the server remains the main copy. That is the usual choice for modern mail apps.
Example: A person reads a message on a phone and the same message is already marked read when they open the laptop.
Ports
- TCP 143 — Cleartext mailbox access
- TCP 993 — Encrypted mailbox access
Common misconception
- Keeping mail on the server is not the protocol that relays a new message to another organization's mail server.