Internet Message Access Protocol (IMAP)

Email Protocol used for managing mails on a mail Server.

Emails are kept on the server and synchronised to one or many clients. This is contrary to POP3 which downloads them to a single Client and deletes the mail from the server afterwards.

It supports creating, renaming, and deleting folders on the server.

By default IMAP use port 143 and when using SSL/TLS port 993.

Commands

Communication is done with text-based commands in ASCII format:

• LOGIN <username> <password>: user’s login.
• LIST "" *: lists all directories.
• CREATE "<mailbox>": creates a mailbox with a specified name.
• DELETE "<mailbox>": deletes a mailbox.
• RENAME "<from name>" "<to name>": renames a mailbox.
• LSUB "" *: returns a subset of subscribed folders.
• SELECT <mailbox>: selects a mailbox so that messages in the mailbox can be accessed.
• UNSELECT <mailbox>: exits the selected mailbox.
• FETCH <ID> all: retrieves data associated with a message in the mailbox.
• CLOSE: removes all messages with the deleted flag set.
• LOGOUT: closes the connection.

You might have to add a alphanumeric prefix in front the commands. This is because IMAP can be done asynchronous with multiple commands.

Examples

Retrieve content of Email

openssl s_client -connect 10.129.179.28:993
a1 login robin robin
a2 list "" *
a3 SELECT "DEV.DEPARTMENT.INT"
a4 FETCH 1 RFC822

These commands login with robin:robin, see available folders, select a folder and retrieves content of first mail in the folder.