Internet Message Access Protocol (IMAP)

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• SMTP is useful only to deliver mail to hosts that are permanently available
  • when a message is received by an SMTP server, it delivers it to a mailbox server
• a mailbox access protocol allows the user’s client email software to operate the mailbox

Internet Message Access Protocol (IMAP) is an application protocol providing a means for a client to access and manage email messages stored in a mailbox on a remote server.

• most widely used mail retrieval protocol
• supports:
  • permanent connections to a server
  • connecting multiple clients to the same mailbox simultaneously
  • allows a client to manage the mailbox on a server and create multiple mailboxes
    • e.g., organize messages in folders, control when they are deleted
• client connects to IMAP server over ports:
  • TCP port 143
    • insecure port used by IMAP4
  • TCP port 993
    • secure port used by IMAPS
    • connection security can be established using TLS
    • default port

Info

In a Windows environment, the proprietary Messaging Application Programming Interface (MAPI) protocol is typically used to access Microsoft Exchange mailboxes.

• uses HTTPS as a secure transport protocol