SMTP(1)                     General Commands Manual                    SMTP(1)

NAME
     smtp - Simple Mail Transfer Protocol client

SYNOPSIS
     smtp [-Chnv] [-a authfile] [-F from] [-H helo] [-s server] [-T params]
          [recipient ...]

DESCRIPTION
     The smtp utility is a Simple Mail Transfer Protocol (SMTP) client which
     can be used to run an SMTP transaction against an SMTP server.

     By default, smtp reads the mail content from the standard input,
     establishes an SMTP session, and runs an SMTP transaction for all the
     specified recipients.  The content is sent unaltered as mail data.

     The options are as follows:

     -a authfile
             Perform a login before sending the message.  The username and
             password are read from authfile and need to be on the first and
             second line respectively.  This option requires a TLS or STARTTLS
             server.

     -C      Do not require server certificate to be valid.  This flag is
             deprecated.  Use "-T noverify" instead.

     -F from
             Set the return-path (MAIL FROM) for the SMTP transaction.
             Default to the current username.

     -H helo
             Define the hostname to advertise (HELO) when establishing the
             SMTP session.

     -h      Display usage.

     -n      Do not actually execute a transaction, just try to establish an
             SMTP session and quit.  When this option is given, no message is
             read from the standard input.

     -s server
             Specify the server to connect to and connection parameters.  The
             format is [proto://[user:pass@]]host[:port].  The following
             protocols are available:

             smtp        Normal SMTP session with opportunistic STARTTLS.
             smtp+tls    Normal SMTP session with mandatory STARTTLS.
             smtp+notls  Plain text SMTP session without TLS.
             lmtp        LMTP session with opportunistic STARTTLS.
             lmtp+tls    LMTP session with mandatory STARTTLS.
             lmtp+notls  Plain text LMTP session without TLS.
             smtps       SMTP session with forced TLS on connection.

             Defaults to "smtp://localhost:25".

     -T params
             Set specific parameters for TLS sessions.  The params string is a
             comma or space separated list of options.  The available options
             are:

             cafile=filename
                     Use filename as root certificates file instead of the
                     system default.

             ciphers=value
                     Specify the allowed ciphers.  Refer to
                     tls_config_set_ciphers(3) for value.

             nosni   Disable Server Name Indication (SNI).

             noverify
                     Do not require server certificate to be valid.

             protocols=value
                     Specify the protocols to use.  Refer to
                     tls_config_parse_protocols(3) for value.

             servername=value
                     Use value for Server Name Indication (SNI).  Defaults to
                     the specified server hostname.

     -v      Be more verbose.  This option can be specified multiple times.

SEE ALSO
     smtpd(8)

HISTORY
     The smtp program first appeared in OpenBSD 6.4.

Linux 6.8.7-arch1-1              May 23, 2021              Linux 6.8.7-arch1-1