.\"	$NetBSD: sendmail.1,v 1.2.14.1 2023/12/25 12:54:40 martin Exp $
.\"
.TH SENDMAIL 1 
.ad
.fi
.SH NAME
sendmail
\-
Postfix to Sendmail compatibility interface
.SH "SYNOPSIS"
.na
.nf
\fBsendmail\fR [\fIoption ...\fR] [\fIrecipient ...\fR]

\fBmailq\fR
\fBsendmail \-bp\fR

\fBnewaliases\fR
\fBsendmail \-I\fR
.SH DESCRIPTION
.ad
.fi
The Postfix \fBsendmail\fR(1) command implements the Postfix
to Sendmail compatibility interface.
For the sake of compatibility with existing applications, some
Sendmail command\-line options are recognized but silently ignored.

By default, Postfix \fBsendmail\fR(1) reads a message from
standard input
until EOF or until it reads a line with only a \fB.\fR character,
and arranges for delivery.  Postfix \fBsendmail\fR(1) relies on the
\fBpostdrop\fR(1) command to create a queue file in the \fBmaildrop\fR
directory.

Specific command aliases are provided for other common modes of
operation:
.IP \fBmailq\fR
List the mail queue. Each entry shows the queue file ID, message
size, arrival time, sender, and the recipients that still need to
be delivered.  If mail could not be delivered upon the last attempt,
the reason for failure is shown. The queue ID string is
followed by an optional status character:
.RS
.IP \fB*\fR
The message is in the \fBactive\fR queue, i.e. the message is
selected for delivery.
.IP \fB!\fR
The message is in the \fBhold\fR queue, i.e. no further delivery
attempt will be made until the mail is taken off hold.
.IP \fB#\fR
The message is forced to expire. See the \fBpostsuper\fR(1)
options \fB\-e\fR or \fB\-f\fR.
.RE
.IP
This mode of operation is implemented by executing the
\fBpostqueue\fR(1) command.
.IP \fBnewaliases\fR
Initialize the alias database.  If no input file is specified (with
the \fB\-oA\fR option, see below), the program processes the file(s)
specified with the \fBalias_database\fR configuration parameter.
If no alias database type is specified, the program uses the type
specified with the \fBdefault_database_type\fR configuration parameter.
This mode of operation is implemented by running the \fBpostalias\fR(1)
command.
.sp
Note: it may take a minute or so before an alias database update
becomes visible. Use the "\fBpostfix reload\fR" command to eliminate
this delay.
.PP
These and other features can be selected by specifying the
appropriate combination of command\-line options. Some features are
controlled by parameters in the \fBmain.cf\fR configuration file.

The following options are recognized:
.IP "\fB\-Am\fR (ignored)"
.IP "\fB\-Ac\fR (ignored)"
Postfix sendmail uses the same configuration file regardless of
whether or not a message is an initial submission.
.IP "\fB\-B \fIbody_type\fR"
The message body MIME type: \fB7BIT\fR or \fB8BITMIME\fR.
.IP \fB\-bd\fR
Go into daemon mode. This mode of operation is implemented by
executing the "\fBpostfix start\fR" command.
.IP "\fB\-bh\fR (ignored)"
.IP "\fB\-bH\fR (ignored)"
Postfix has no persistent host status database.
.IP \fB\-bi\fR
Initialize alias database. See the \fBnewaliases\fR
command above.
.IP \fB\-bl\fR
Go into daemon mode. To accept only local connections as
with Sendmail's \fB\-bl\fR option, specify "\fBinet_interfaces
= loopback\fR" in the Postfix \fBmain.cf\fR configuration
file.
.IP \fB\-bm\fR
Read mail from standard input and arrange for delivery.
This is the default mode of operation.
.IP \fB\-bp\fR
List the mail queue. See the \fBmailq\fR command above.
.IP \fB\-bs\fR
Stand\-alone SMTP server mode. Read SMTP commands from
standard input, and write responses to standard output.
In stand\-alone SMTP server mode, mail relaying and other
access controls are disabled by default. To enable them,
run the process as the \fBmail_owner\fR user.
.sp
This mode of operation is implemented by running the
\fBsmtpd\fR(8) daemon.
.IP \fB\-bv\fR
Do not collect or deliver a message. Instead, send an email
report after verifying each recipient address.  This is useful
for testing address rewriting and routing configurations.
.sp
This feature is available in Postfix version 2.1 and later.
.IP "\fB\-C \fIconfig_file\fR"
.IP "\fB\-C \fIconfig_dir\fR"
The path name of the Postfix \fBmain.cf\fR file, or of its
parent directory. This information is ignored with Postfix
versions before 2.3.

With Postfix version 3.2 and later, a non\-default directory
must be authorized in the default \fBmain.cf\fR file, through
the alternate_config_directories or multi_instance_directories
parameters.

With all Postfix versions, you can specify a directory pathname
with the MAIL_CONFIG environment variable to override the
location of configuration files.
.IP "\fB\-F \fIfull_name\fR"
Set the sender full name. This overrides the NAME environment
variable, and is used only with messages that
have no \fBFrom:\fR message header.
.IP "\fB\-f \fIsender\fR"
Set the envelope sender address. This is the address where
delivery problems are sent to. With Postfix versions before 2.1, the
\fBErrors\-To:\fR message header overrides the error return address.
.IP \fB\-G\fR
Gateway (relay) submission, as opposed to initial user
submission.  Either do not rewrite addresses at all, or
update incomplete addresses with the domain information
specified with \fBremote_header_rewrite_domain\fR.

This option is ignored before Postfix version 2.3.
.IP "\fB\-h \fIhop_count\fR (ignored)"
Hop count limit. Use the \fBhopcount_limit\fR configuration
parameter instead.
.IP \fB\-I\fR
Initialize alias database. See the \fBnewaliases\fR
command above.
.IP "\fB\-i\fR"
When reading a message from standard input, don't treat a line
with only a \fB.\fR character as the end of input.
.IP "\fB\-L \fIlabel\fR (ignored)"
The logging label. Use the \fBsyslog_name\fR configuration
parameter instead.
.IP "\fB\-m\fR (ignored)"
Backwards compatibility.
.IP "\fB\-N \fIdsn\fR (default: 'delay, failure')"
Delivery status notification control. Specify either a
comma\-separated list with one or more of \fBfailure\fR (send
notification when delivery fails), \fBdelay\fR (send
notification when delivery is delayed), or \fBsuccess\fR
(send notification when the message is delivered); or specify
\fBnever\fR (don't send any notifications at all).

This feature is available in Postfix 2.3 and later.
.IP "\fB\-n\fR (ignored)"
Backwards compatibility.
.IP "\fB\-oA\fIalias_database\fR"
Non\-default alias database. Specify \fIpathname\fR or
\fItype\fR:\fIpathname\fR. See \fBpostalias\fR(1) for
details.
.IP "\fB\-O \fIoption=value\fR (ignored)"
Set the named \fIoption\fR to \fIvalue\fR. Use the equivalent
configuration parameter in \fBmain.cf\fR instead.
.IP "\fB\-o7\fR (ignored)"
.IP "\fB\-o8\fR (ignored)"
To send 8\-bit or binary content, use an appropriate MIME encapsulation
and specify the appropriate \fB\-B\fR command\-line option.
.IP "\fB\-oi\fR"
When reading a message from standard input, don't treat a line
with only a \fB.\fR character as the end of input.
.IP "\fB\-om\fR (ignored)"
The sender is never eliminated from alias etc. expansions.
.IP "\fB\-o \fIx value\fR (ignored)"
Set option \fIx\fR to \fIvalue\fR. Use the equivalent
configuration parameter in \fBmain.cf\fR instead.
.IP "\fB\-r \fIsender\fR"
Set the envelope sender address. This is the address where
delivery problems are sent to. With Postfix versions before 2.1, the
\fBErrors\-To:\fR message header overrides the error return address.
.IP "\fB\-R \fIreturn\fR"
Delivery status notification control.  Specify "hdrs" to
return only the header when a message bounces, "full" to
return a full copy (the default behavior).

The \fB\-R\fR option specifies an upper bound; Postfix will
return only the header, when a full copy would exceed the
bounce_size_limit setting.

This option is ignored before Postfix version 2.10.
.IP \fB\-q\fR
Attempt to deliver all queued mail. This is implemented by
executing the \fBpostqueue\fR(1) command.

Warning: flushing undeliverable mail frequently will result in
poor delivery performance of all other mail.
.IP "\fB\-q\fIinterval\fR (ignored)"
The interval between queue runs. Use the \fBqueue_run_delay\fR
configuration parameter instead.
.IP \fB\-qI\fIqueueid\fR
Schedule immediate delivery of mail with the specified queue
ID.  This option is implemented by executing the
\fBpostqueue\fR(1) command, and is available with Postfix
version 2.4 and later.
.IP \fB\-qR\fIsite\fR
Schedule immediate delivery of all mail that is queued for the named
\fIsite\fR. This option accepts only \fIsite\fR names that are
eligible for the "fast flush" service, and is implemented by
executing the \fBpostqueue\fR(1) command.
See \fBflush\fR(8) for more information about the "fast flush"
service.
.IP \fB\-qS\fIsite\fR
This command is not implemented. Use the slower "\fBsendmail \-q\fR"
command instead.
.IP \fB\-t\fR
Extract recipients from message headers. These are added to any
recipients specified on the command line.

With Postfix versions prior to 2.1, this option requires that
no recipient addresses are specified on the command line.
.IP "\fB\-U\fR (ignored)"
Initial user submission.
.IP "\fB\-V \fIenvid\fR"
Specify the envelope ID for notification by servers that
support DSN.

This feature is available in Postfix 2.3 and later.
.IP "\fB\-XV\fR (Postfix 2.2 and earlier: \fB\-V\fR)"
Variable Envelope Return Path. Given an envelope sender address
of the form \fIowner\-listname\fR@\fIorigin\fR, each recipient
\fIuser\fR@\fIdomain\fR receives mail with a personalized envelope
sender address.
.sp
By default, the personalized envelope sender address is
\fIowner\-listname\fB+\fIuser\fB=\fIdomain\fR@\fIorigin\fR. The default
\fB+\fR and \fB=\fR characters are configurable with the
\fBdefault_verp_delimiters\fR configuration parameter.
.IP "\fB\-XV\fIxy\fR (Postfix 2.2 and earlier: \fB\-V\fIxy\fR)"
As \fB\-XV\fR, but uses \fIx\fR and \fIy\fR as the VERP delimiter
characters, instead of the characters specified with the
\fBdefault_verp_delimiters\fR configuration parameter.
.IP \fB\-v\fR
Send an email report of the first delivery attempt (Postfix
versions 2.1 and later). Mail delivery
always happens in the background. When multiple \fB\-v\fR
options are given, enable verbose logging for debugging purposes.
.IP "\fB\-X \fIlog_file\fR (ignored)"
Log mailer traffic. Use the \fBdebug_peer_list\fR and
\fBdebug_peer_level\fR configuration parameters instead.
.SH "SECURITY"
.na
.nf
.ad
.fi
By design, this program is not set\-user (or group) id.
It is prepared to handle message content from untrusted,
possibly remote, users.

However, like most Postfix programs, this program does not
enforce a security policy on its command\-line arguments.
Instead, it relies on the UNIX system to enforce access
policies based on the effective user and group IDs of the
process. Concretely, this means that running Postfix commands
as root (from sudo or equivalent) on behalf of a non\-root
user is likely to create privilege escalation opportunities.

If an application runs any Postfix programs on behalf of
users that do not have normal shell access to Postfix
commands, then that application MUST restrict user\-specified
command\-line arguments to avoid privilege escalation.
.IP \(bu
Filter all command\-line arguments, for example arguments
that contain a pathname or that specify a database access
method. These pathname checks must reject user\-controlled
symlinks or hardlinks to sensitive files, and must not be
vulnerable to TOCTOU race attacks.
.IP \(bu
Disable command options processing for all command arguments
that contain user\-specified data. For example, the Postfix
\fBsendmail\fR(1) command line MUST be structured as follows:

.nf
    \fB/path/to/sendmail\fR \fIsystem\-arguments\fR \fB\-\-\fR \fIuser\-arguments\fR
.fi

Here, the "\fB\-\-\fR" disables command option processing for
all \fIuser\-arguments\fR that follow.
.IP
Without the "\fB\-\-\fR", a malicious user could enable Postfix
\fBsendmail\fR(1) command options, by specifying an email
address that starts with "\fB\-\fR".
.SH DIAGNOSTICS
.ad
.fi
Problems are logged to \fBsyslogd\fR(8) or \fBpostlogd\fR(8),
and to the standard error stream.
.SH "ENVIRONMENT"
.na
.nf
.ad
.fi
.IP \fBMAIL_CONFIG\fR
Directory with Postfix configuration files.
.IP "\fBMAIL_VERBOSE\fR (value does not matter)"
Enable verbose logging for debugging purposes.
.IP "\fBMAIL_DEBUG\fR (value does not matter)"
Enable debugging with an external command, as specified with the
\fBdebugger_command\fR configuration parameter.
.IP \fBNAME\fR
The sender full name. This is used only with messages that
have no \fBFrom:\fR message header. See also the \fB\-F\fR
option above.
.SH "CONFIGURATION PARAMETERS"
.na
.nf
.ad
.fi
The following \fBmain.cf\fR parameters are especially relevant to
this program.
The text below provides only a parameter summary. See
\fBpostconf\fR(5) for more details including examples.
.SH "COMPATIBILITY CONTROLS"
.na
.nf
.ad
.fi
Available with Postfix 2.9 and later:
.IP "\fBsendmail_fix_line_endings (always)\fR"
Controls how the Postfix sendmail command converts email message
line endings from <CR><LF> into UNIX format (<LF>).
.SH "TROUBLE SHOOTING CONTROLS"
.na
.nf
.ad
.fi
The DEBUG_README file gives examples of how to troubleshoot a
Postfix system.
.IP "\fBdebugger_command (empty)\fR"
The external command to execute when a Postfix daemon program is
invoked with the \-D option.
.IP "\fBdebug_peer_level (2)\fR"
The increment in verbose logging level when a nexthop destination,
remote client or server name or network address matches a pattern
given with the debug_peer_list parameter.
.IP "\fBdebug_peer_list (empty)\fR"
Optional list of nexthop destination, remote client or server
name or network address patterns that, if matched, cause the verbose
logging level to increase by the amount specified in $debug_peer_level.
.SH "ACCESS CONTROLS"
.na
.nf
.ad
.fi
Available in Postfix version 2.2 and later:
.IP "\fBauthorized_flush_users (static:anyone)\fR"
List of users who are authorized to flush the queue.
.IP "\fBauthorized_mailq_users (static:anyone)\fR"
List of users who are authorized to view the queue.
.IP "\fBauthorized_submit_users (static:anyone)\fR"
List of users who are authorized to submit mail with the \fBsendmail\fR(1)
command (and with the privileged \fBpostdrop\fR(1) helper command).
.SH "RESOURCE AND RATE CONTROLS"
.na
.nf
.ad
.fi
.IP "\fBbounce_size_limit (50000)\fR"
The maximal amount of original message text that is sent in a
non\-delivery notification.
.IP "\fBfork_attempts (5)\fR"
The maximal number of attempts to fork() a child process.
.IP "\fBfork_delay (1s)\fR"
The delay between attempts to fork() a child process.
.IP "\fBhopcount_limit (50)\fR"
The maximal number of Received:  message headers that is allowed
in the primary message headers.
.IP "\fBqueue_run_delay (300s)\fR"
The time between deferred queue scans by the queue manager;
prior to Postfix 2.4 the default value was 1000s.
.SH "FAST FLUSH CONTROLS"
.na
.nf
.ad
.fi
The ETRN_README file describes configuration and operation
details for the Postfix "fast flush" service.
.IP "\fBfast_flush_domains ($relay_domains)\fR"
Optional list of destinations that are eligible for per\-destination
logfiles with mail that is queued to those destinations.
.SH "VERP CONTROLS"
.na
.nf
.ad
.fi
The VERP_README file describes configuration and operation
details of Postfix support for variable envelope return
path addresses.
.IP "\fBdefault_verp_delimiters (+=)\fR"
The two default VERP delimiter characters.
.IP "\fBverp_delimiter_filter (\-=+)\fR"
The characters Postfix accepts as VERP delimiter characters on the
Postfix \fBsendmail\fR(1) command line and in SMTP commands.
.SH "MISCELLANEOUS CONTROLS"
.na
.nf
.ad
.fi
.IP "\fBalias_database (see 'postconf -d' output)\fR"
The alias databases for \fBlocal\fR(8) delivery that are updated with
"\fBnewaliases\fR" or with "\fBsendmail \-bi\fR".
.IP "\fBcommand_directory (see 'postconf -d' output)\fR"
The location of all postfix administrative commands.
.IP "\fBconfig_directory (see 'postconf -d' output)\fR"
The default location of the Postfix main.cf and master.cf
configuration files.
.IP "\fBdaemon_directory (see 'postconf -d' output)\fR"
The directory with Postfix support programs and daemon programs.
.IP "\fBdefault_database_type (see 'postconf -d' output)\fR"
The default database type for use in \fBnewaliases\fR(1), \fBpostalias\fR(1)
and \fBpostmap\fR(1) commands.
.IP "\fBdelay_warning_time (0h)\fR"
The time after which the sender receives a copy of the message
headers of mail that is still queued.
.IP "\fBimport_environment (see 'postconf -d' output)\fR"
The list of environment variables that a privileged Postfix
process will import from a non\-Postfix parent process, or name=value
environment overrides.
.IP "\fBmail_owner (postfix)\fR"
The UNIX system account that owns the Postfix queue and most Postfix
daemon processes.
.IP "\fBqueue_directory (see 'postconf -d' output)\fR"
The location of the Postfix top\-level queue directory.
.IP "\fBremote_header_rewrite_domain (empty)\fR"
Don't rewrite message headers from remote clients at all when
this parameter is empty; otherwise, rewrite message headers and
append the specified domain name to incomplete addresses.
.IP "\fBsyslog_facility (mail)\fR"
The syslog facility of Postfix logging.
.IP "\fBsyslog_name (see 'postconf -d' output)\fR"
A prefix that is prepended to the process name in syslog
records, so that, for example, "smtpd" becomes "prefix/smtpd".
.PP
Postfix 3.2 and later:
.IP "\fBalternate_config_directories (empty)\fR"
A list of non\-default Postfix configuration directories that may
be specified with "\-c config_directory" on the command line (in the
case of \fBsendmail\fR(1), with the "\-C" option), or via the MAIL_CONFIG
environment parameter.
.IP "\fBmulti_instance_directories (empty)\fR"
An optional list of non\-default Postfix configuration directories;
these directories belong to additional Postfix instances that share
the Postfix executable files and documentation with the default
Postfix instance, and that are started, stopped, etc., together
with the default Postfix instance.
.SH "FILES"
.na
.nf
/var/spool/postfix, mail queue
/etc/postfix, configuration files
.SH "SEE ALSO"
.na
.nf
pickup(8), mail pickup daemon
qmgr(8), queue manager
smtpd(8), SMTP server
flush(8), fast flush service
postsuper(1), queue maintenance
postalias(1), create/update/query alias database
postdrop(1), mail posting utility
postfix(1), mail system control
postqueue(1), mail queue control
postlogd(8), Postfix logging
syslogd(8), system logging
.SH "README_FILES"
.na
.nf
.ad
.fi
Use "\fBpostconf readme_directory\fR" or
"\fBpostconf html_directory\fR" to locate this information.
.na
.nf
DEBUG_README, Postfix debugging howto
ETRN_README, Postfix ETRN howto
VERP_README, Postfix VERP howto
.SH "LICENSE"
.na
.nf
.ad
.fi
The Secure Mailer license must be distributed with this software.
.SH "AUTHOR(S)"
.na
.nf
Wietse Venema
IBM T.J. Watson Research
P.O. Box 704
Yorktown Heights, NY 10598, USA

Wietse Venema
Google, Inc.
111 8th Avenue
New York, NY 10011, USA