msmtp is an SMTP client that one can use with mail user agents that
that contain no mail transfer capability (e.g., Mutt).

Supported features:
- sendmail compatible interface (command line options and exit codes)
- SMTP AUTH methods PLAIN, LOGIN, CRAM-MD5 and EXTERNAL
(and GSSAPI, DIGEST-MD5 and NTLM when compiled with GNU SASL support)
- TLS encrypted connections with the GnuTLS or OpenSSL libraries
(including server certificate verification and the possibility to send
a client certificate)
- LMTP support
- DSN (Delivery Status Notification) support
- RMQS (Remote Message Queue Starting) support (ETRN keyword)
- PIPELINING support for increased transmission speed
- IPv6 support
- support for multiple accounts