Local Mail Transfer Protocol
The Local Mail Transfer Protocol or LMTP is a derivate of SMTP, the Simple Mail Transfer Protocol.
It is designed as an alternative to normal SMTP for situations where the receiving side does not have a mail queue, such as a Mail Delivery Agent MDA that understands SMTP conversations.
LMTP is an application level protocol, which runs on top of TCP/IP.
Although a LMTP conversation uses the same commands as a SMTP conversation, one is not supposed to run an LMTP server on the TCP/25 port.