.\"	$OpenBSD: smtp.1,v 1.14 2021/05/23 16:12:56 eric Exp $
.\"
.\" Copyright (c) 2018, Eric Faurot <eric@openbsd.org>
.\"
.\" Permission to use, copy, modify, and distribute this software for any
.\" purpose with or without fee is hereby granted, provided that the above
.\" copyright notice and this permission notice appear in all copies.
.\"
.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
.\"
.Dd $Mdocdate: May 23 2021 $
.Dt SMTP 1
.Os
.Sh NAME
.Nm smtp
.Nd Simple Mail Transfer Protocol client
.Sh SYNOPSIS
.Nm
.Op Fl Chnv
.Op Fl a Ar authfile
.Op Fl F Ar from
.Op Fl H Ar helo
.Op Fl s Ar server
.Op Fl T Ar params
.Op Ar recipient ...
.Sh DESCRIPTION
The
.Nm
utility is a Simple Mail Transfer Protocol
.Pq SMTP
client which can be used to run an SMTP transaction against an SMTP server.
.Pp
By default,
.Nm
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.
.Pp
The options are as follows:
.Bl -tag -width Ds
.It Fl a Ar authfile
Perform a login before sending the message.
The username and password are read from
.Ar authfile
and need to be on the first and second line respectively.
This option requires a TLS or STARTTLS
.Ar server .
.It Fl C
Do not require server certificate to be valid.
This flag is deprecated.
Use
.Dq Fl T Cm noverify
instead.
.It Fl F Ar from
Set the return-path (MAIL FROM) for the SMTP transaction.
Default to the current username.
.It Fl H Ar helo
Define the hostname to advertise (HELO) when establishing the SMTP session.
.It Fl h
Display usage.
.It Fl 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.
.It Fl s Ar server
Specify the server to connect to and connection parameters.
The format is
.Sm off
.Op Ar proto No :// Op Ar user : pass No @
.Ar host Op : Ar port .
.Sm on
The following protocols are available:
.Pp
.Bl -tag -width "smtp+notls" -compact
.It smtp
Normal SMTP session with opportunistic STARTTLS.
.It smtp+tls
Normal SMTP session with mandatory STARTTLS.
.It smtp+notls
Plain text SMTP session without TLS.
.It lmtp
LMTP session with opportunistic STARTTLS.
.It lmtp+tls
LMTP session with mandatory STARTTLS.
.It lmtp+notls
Plain text LMTP session without TLS.
.It smtps
SMTP session with forced TLS on connection.
.El
.Pp
Defaults to
.Dq smtp://localhost:25 .
.It Fl T Ar params
Set specific parameters for TLS sessions.
The
.Ar params
string is a comma or space separated list of options.
The available options are:
.Bl -tag -width Ds
.It Cm cafile Ns = Ns Ar filename
Use
.Ar filename
as root certificates file instead of the system default.
.It Cm ciphers Ns = Ns Ar value
Specify the allowed ciphers.
Refer to
.Xr tls_config_set_ciphers 3
for
.Ar value .
.It Cm nosni
Disable Server Name Indication (SNI).
.It Cm noverify
Do not require server certificate to be valid.
.It Cm protocols Ns = Ns Ar value
Specify the protocols to use.
Refer to
.Xr tls_config_parse_protocols 3
for
.Ar value .
.It Cm servername Ns = Ns Ar value
Use
.Ar value
for Server Name Indication (SNI).
Defaults to the specified server hostname.
.El
.It Fl v
Be more verbose.
This option can be specified multiple times.
.El
.Sh SEE ALSO
.Xr smtpd 8
.Sh HISTORY
The
.Nm
program first appeared in
.Ox 6.4 .