I've previously documented running Sendmail in a zone. One of the things that I need for testing Sendmail is a source of messages, and an easy mechanism to get them to Sendmail over SMTP.
A program that I've been aware of for some time that does exactly that is
smtp-source. It ships as part of Postfix, and there's an smtp-souce(1) manual page, which says:
smtp-source connects to the named host and TCP port (default: port 25) and sends one or more messages to it, either sequentially or in parallel. The program speaks either SMTP (default) or LMTP. Connections can be made to UNIX-domain and IPv4 or IPv6 servers. IPv4 and IPv6 are the default.
Building was trivially easy. After downloading and unpacking Postfix 2.3.1, it was enough to:
% cd postfix-2.3.1
% make makefiles CC=/opt/SUNWspro/bin/cc
which, amongst other things, built