Updated: 2022/Sep/29
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SENDMAIL(1) General Commands Manual SENDMAIL(1)
NAME
sendmail - Postfix to Sendmail compatibility interface
SYNOPSIS
sendmail [option ...] [recipient ...]
mailq
sendmail -bp
newaliases
sendmail -I
DESCRIPTION
The Postfix sendmail(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 sendmail(1) reads a message from standard input
until EOF or until it reads a line with only a . character, and
arranges for delivery. Postfix sendmail(1) relies on the postdrop(1)
command to create a queue file in the maildrop directory.
Specific command aliases are provided for other common modes of
operation:
mailq 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:
* The message is in the active queue, i.e. the message is
selected for delivery.
! The message is in the hold queue, i.e. no further
delivery attempt will be made until the mail is taken off
hold.
# The message is forced to expire. See the postsuper(1)
options -e or -f.
This mode of operation is implemented by executing the
postqueue(1) command.
newaliases
Initialize the alias database. If no input file is specified
(with the -oA option, see below), the program processes the
file(s) specified with the alias_database configuration
parameter. If no alias database type is specified, the program
uses the type specified with the default_database_type
configuration parameter. This mode of operation is implemented
by running the postalias(1) command.
Note: it may take a minute or so before an alias database update
becomes visible. Use the "postfix reload" command to eliminate
this delay.
These and other features can be selected by specifying the appropriate
combination of command-line options. Some features are controlled by
parameters in the main.cf configuration file.
The following options are recognized:
-Am (ignored)
-Ac (ignored)
Postfix sendmail uses the same configuration file regardless of
whether or not a message is an initial submission.
-B body_type
The message body MIME type: 7BIT or 8BITMIME.
-bd Go into daemon mode. This mode of operation is implemented by
executing the "postfix start" command.
-bh (ignored)
-bH (ignored)
Postfix has no persistent host status database.
-bi Initialize alias database. See the newaliases command above.
-bl Go into daemon mode. To accept only local connections as with
Sendmail's -bl option, specify "inet_interfaces = loopback" in
the Postfix main.cf configuration file.
-bm Read mail from standard input and arrange for delivery. This is
the default mode of operation.
-bp List the mail queue. See the mailq command above.
-bs 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
mail_owner user.
This mode of operation is implemented by running the smtpd(8)
daemon.
-bv 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.
This feature is available in Postfix version 2.1 and later.
-C config_file
-C config_dir
The path name of the Postfix main.cf 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 main.cf 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.
-F full_name
Set the sender full name. This overrides the NAME environment
variable, and is used only with messages that have no From:
message header.
-f sender
Set the envelope sender address. This is the address where
delivery problems are sent to. With Postfix versions before 2.1,
the Errors-To: message header overrides the error return
address.
-G 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
remote_header_rewrite_domain.
This option is ignored before Postfix version 2.3.
-h hop_count (ignored)
Hop count limit. Use the hopcount_limit configuration parameter
instead.
-I Initialize alias database. See the newaliases command above.
-i When reading a message from standard input, don't treat a line
with only a . character as the end of input.
-L label (ignored)
The logging label. Use the syslog_name configuration parameter
instead.
-m (ignored)
Backwards compatibility.
-N dsn (default: 'delay, failure')
Delivery status notification control. Specify either a
comma-separated list with one or more of failure (send
notification when delivery fails), delay (send notification when
delivery is delayed), or success (send notification when the
message is delivered); or specify never (don't send any
notifications at all).
This feature is available in Postfix 2.3 and later.
-n (ignored)
Backwards compatibility.
-oAalias_database
Non-default alias database. Specify pathname or type:pathname.
See postalias(1) for details.
-O option=value (ignored)
Set the named option to value. Use the equivalent configuration
parameter in main.cf instead.
-o7 (ignored)
-o8 (ignored)
To send 8-bit or binary content, use an appropriate MIME
encapsulation and specify the appropriate -B command-line
option.
-oi When reading a message from standard input, don't treat a line
with only a . character as the end of input.
-om (ignored)
The sender is never eliminated from alias etc. expansions.
-o x value (ignored)
Set option x to value. Use the equivalent configuration
parameter in main.cf instead.
-r sender
Set the envelope sender address. This is the address where
delivery problems are sent to. With Postfix versions before 2.1,
the Errors-To: message header overrides the error return
address.
-R return
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 -R 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.
-q Attempt to deliver all queued mail. This is implemented by
executing the postqueue(1) command.
Warning: flushing undeliverable mail frequently will result in
poor delivery performance of all other mail.
-qinterval (ignored)
The interval between queue runs. Use the queue_run_delay
configuration parameter instead.
-qIqueueid
Schedule immediate delivery of mail with the specified queue ID.
This option is implemented by executing the postqueue(1)
command, and is available with Postfix version 2.4 and later.
-qRsite
Schedule immediate delivery of all mail that is queued for the
named site. This option accepts only site names that are
eligible for the "fast flush" service, and is implemented by
executing the postqueue(1) command. See flush(8) for more
information about the "fast flush" service.
-qSsite
This command is not implemented. Use the slower "sendmail -q"
command instead.
-t 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.
-U (ignored)
Initial user submission.
-V envid
Specify the envelope ID for notification by servers that support
DSN.
This feature is available in Postfix 2.3 and later.
-XV (Postfix 2.2 and earlier: -V)
Variable Envelope Return Path. Given an envelope sender address
of the form owner-listname@origin, each recipient user@domain
receives mail with a personalized envelope sender address.
By default, the personalized envelope sender address is
owner-listname+user=domain@origin. The default + and =
characters are configurable with the default_verp_delimiters
configuration parameter.
-XVxy (Postfix 2.2 and earlier: -Vxy)
As -XV, but uses x and y as the VERP delimiter characters,
instead of the characters specified with the
default_verp_delimiters configuration parameter.
-v Send an email report of the first delivery attempt (Postfix
versions 2.1 and later). Mail delivery always happens in the
background. When multiple -v options are given, enable verbose
logging for debugging purposes.
-X log_file (ignored)
Log mailer traffic. Use the debug_peer_list and debug_peer_level
configuration parameters instead.
SECURITY
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.
⊕ 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.
⊕ Disable command options processing for all command arguments
that contain user-specified data. For example, the Postfix
sendmail(1) command line MUST be structured as follows:
/path/to/sendmail system-arguments -- user-arguments
Here, the "--" disables command option processing for all
user-arguments that follow.
Without the "--", a malicious user could enable Postfix
sendmail(1) command options, by specifying an email address that
starts with "-".
DIAGNOSTICS
Problems are logged to syslogd(8) or postlogd(8), and to the standard
error stream.
ENVIRONMENT
MAIL_CONFIG
Directory with Postfix configuration files.
MAIL_VERBOSE (value does not matter)
Enable verbose logging for debugging purposes.
MAIL_DEBUG (value does not matter)
Enable debugging with an external command, as specified with the
debugger_command configuration parameter.
NAME The sender full name. This is used only with messages that have
no From: message header. See also the -F option above.
CONFIGURATION PARAMETERS
The following main.cf parameters are especially relevant to this
program. The text below provides only a parameter summary. See
postconf(5) for more details including examples.
COMPATIBILITY CONTROLS
Available with Postfix 2.9 and later:
sendmail_fix_line_endings (always)
Controls how the Postfix sendmail command converts email message
line endings from <CR><LF> into UNIX format (<LF>).
TROUBLE SHOOTING CONTROLS
The DEBUG_README file gives examples of how to troubleshoot a Postfix
system.
debugger_command (empty)
The external command to execute when a Postfix daemon program is
invoked with the -D option.
debug_peer_level (2)
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.
debug_peer_list (empty)
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
$debug_peer_level.
ACCESS CONTROLS
Available in Postfix version 2.2 and later:
authorized_flush_users (static:anyone)
List of users who are authorized to flush the queue.
authorized_mailq_users (static:anyone)
List of users who are authorized to view the queue.
authorized_submit_users (static:anyone)
List of users who are authorized to submit mail with the
sendmail(1) command (and with the privileged postdrop(1) helper
command).
RESOURCE AND RATE CONTROLS
bounce_size_limit (50000)
The maximal amount of original message text that is sent in a
non-delivery notification.
fork_attempts (5)
The maximal number of attempts to fork() a child process.
fork_delay (1s)
The delay between attempts to fork() a child process.
hopcount_limit (50)
The maximal number of Received: message headers that is allowed
in the primary message headers.
queue_run_delay (300s)
The time between deferred queue scans by the queue manager;
prior to Postfix 2.4 the default value was 1000s.
FAST FLUSH CONTROLS
The ETRN_README file describes configuration and operation details for
the Postfix "fast flush" service.
fast_flush_domains ($relay_domains)
Optional list of destinations that are eligible for
per-destination logfiles with mail that is queued to those
destinations.
VERP CONTROLS
The VERP_README file describes configuration and operation details of
Postfix support for variable envelope return path addresses.
default_verp_delimiters (+=)
The two default VERP delimiter characters.
verp_delimiter_filter (-=+)
The characters Postfix accepts as VERP delimiter characters on
the Postfix sendmail(1) command line and in SMTP commands.
MISCELLANEOUS CONTROLS
alias_database (see 'postconf -d' output)
The alias databases for local(8) delivery that are updated with
"newaliases" or with "sendmail -bi".
command_directory (see 'postconf -d' output)
The location of all postfix administrative commands.
config_directory (see 'postconf -d' output)
The default location of the Postfix main.cf and master.cf
configuration files.
daemon_directory (see 'postconf -d' output)
The directory with Postfix support programs and daemon programs.
default_database_type (see 'postconf -d' output)
The default database type for use in newaliases(1), postalias(1)
and postmap(1) commands.
delay_warning_time (0h)
The time after which the sender receives a copy of the message
headers of mail that is still queued.
import_environment (see 'postconf -d' output)
The list of environment variables that a privileged Postfix
process will import from a non-Postfix parent process, or
name=value environment overrides.
mail_owner (postfix)
The UNIX system account that owns the Postfix queue and most
Postfix daemon processes.
queue_directory (see 'postconf -d' output)
The location of the Postfix top-level queue directory.
remote_header_rewrite_domain (empty)
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.
syslog_facility (mail)
The syslog facility of Postfix logging.
syslog_name (see 'postconf -d' output)
A prefix that is prepended to the process name in syslog
records, so that, for example, "smtpd" becomes "prefix/smtpd".
Postfix 3.2 and later:
alternate_config_directories (empty)
A list of non-default Postfix configuration directories that may
be specified with "-c config_directory" on the command line (in
the case of sendmail(1), with the "-C" option), or via the
MAIL_CONFIG environment parameter.
multi_instance_directories (empty)
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.
FILES
/var/spool/postfix, mail queue
/etc/postfix, configuration files
SEE ALSO
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
README_FILES
Use "postconf readme_directory" or "postconf html_directory" to locate
this information.
DEBUG_README, Postfix debugging howto
ETRN_README, Postfix ETRN howto
VERP_README, Postfix VERP howto
LICENSE
The Secure Mailer license must be distributed with this software.
AUTHOR(S)
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
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