1.4 Relationship to Other Protocols
The NTLM POP3 Extension uses the POP3 AUTH extension mechanism, as specified in [RFC1734], and is an embedded protocol. Unlike standalone application protocols, such as Telnet or Hypertext Transfer Protocol (HTTP), packets for this specification are embedded in POP3 commands and server responses.
POP3 specifies only the sequence in which a POP3 server and POP3 client exchange NTLM messages to successfully authenticate the client to the server. It does not specify how the client obtains NTLM messages from the local NTLM software, or how the POP3 server processes NTLM messages. The POP3 client and POP3 server implementations depend on the availability of an implementation of the NTLM Authentication Protocol (as specified in [MS-NLMP]) to obtain and process NTLM messages and on the availability of the base64 encoding and decoding mechanisms (as specified in [RFC1521]) to encode and decode the NTLM messages embedded in POP3 packets.