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.