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.

Debian                                            May 23, 2021                                           SMTP(1)