Você precisa testar se um servidor smtp funciona ou enviar alguns e-mails usando um script de shell?
SWAKS - Canivete suíço para SMTP
Swaks is a featureful, flexible, scriptable, transaction-oriented
SMTP test tool written and maintained by John Jetmore. Features include:
* SMTP extensions including TLS, authentication, and pipelining
* Protocols including SMTP, ESMTP, and LMTP
* Transports including unix-domain sockets, internet-domain sockets
(IPv4 and IPv6), and pipes to spawned processes
* Completely scriptable configuration, with option specification
via environment variables, configuration files, and command line