The LMTP class
RFC 2033 defines the Local Mail Transport Protocol. In many ways, this is very similar to SMTP, but with no guarantees of queuing. It is, in a sense, an alternative to ESMTP, and is often used for local mail routing (e.g. from a Mail Transport Agent to a local command or system) where the unreliability of internet connectivity is not an issue.
LMTP class subclasses the
and its only functional difference is that
it implements the
and prohibits the use of