Port 143 is the port used by the Internet Message Access Protocol (IMAP).
IMAP and Port 143
IMAP (Internet Message Access Protocol) is an application layer Internet protocol used by email clients to retrieve email messages from a mail server over a TCP/IP connection. It allows users to access and manage their email on a server. The standard port assigned to IMAP is port 143.
Key characteristics of IMAP:
- Server-based: IMAP stores emails on the server, allowing access from multiple devices.
- Two-way communication: Changes made on a client (e.g., marking an email as read) are reflected on the server and across other clients.
- Message management: Supports features such as creating, deleting, and renaming mailboxes (folders) on the server.
Alternatives and Secure IMAP
While port 143 is the standard for IMAP, a secure version, IMAPS (IMAP over SSL/TLS), operates on port 993. IMAPS encrypts the communication between the client and the server, protecting the email data from eavesdropping.
| Protocol | Port | Security | Description |
|---|---|---|---|
| IMAP | 143 | No | Standard IMAP for retrieving email. |
| IMAPS | 993 | Yes | Secure IMAP, using SSL/TLS encryption for secure email retrieval. |
Other Relevant Ports
It's helpful to understand the context of port 143 by looking at other related ports:
- Port 139: NetBIOS Session Service. This is related to file and printer sharing on Windows networks.
- Port 993: IMAPS (IMAP over SSL/TLS). This is the secure version of IMAP.
- Port 25: SMTP (Simple Mail Transfer Protocol) - used for sending email.
- Port 110: POP3 (Post Office Protocol version 3) - another protocol for retrieving email (less feature-rich than IMAP).
