(LMTP) A protocol designed as an alternative to esmtp for cases where the mail receiver does not manage a queue. LMTP is an application level protocol that runs on top of tcp/ip. It was initially defined in rfc 2033, and uses (with a few changes) the syntax and semantics of esmtp. It should be used only by specific prior arrangement and configuration, and it must not be used on TCP port 25 (the smtp port).