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sendmail(8)
NAME
sendmail, newaliases, mailq, smtpd - Sends mail over the Internet
SYNOPSIS
/usr/sbin/sendmail [-flags] [address ...]
/usr/sbin/newaliases
/usr/sbin/mailq [-v]
/usr/sbin/smtpd
FLAGS
-Btype
Set the body type to type. The current values are "7BIT" or "8BITMIME".
[Version 8 only]
-ba Goes into ARPANET mode. All input lines must end with a CR-LF, and all
messages will be generated with a CR-LF at the end. Also, the From:
and Sender: fields are examined for the name of the sender.
-bd Runs as a daemon. This requires Berkeley Interprocess Communications
(IPC). The sendmail command will fork and run in the background,
listening on the socket specified in the /etc/services file for
incoming SMTP (Simple Mail Transfer Protocol) connections. This is
normally run when going to multiuser mode.
Using this flag is equivalent to invoking sendmail as smtpd.
-bD This flag is the same as the -bd flag, except that it runs the
foreground. This flag can be used for debugging purposes. [Version 8
only]
-bi Initializes the alias database. This is the same as invoking the
newaliases command.
-bm Delivers mail in the usual way (default).
-bp Prints a listing of the queue. This is the same as invoking the
mailq command.
-bs Use the SMTP protocol as described in RFC821 on standard input and
output. This flag implies all the operations of the -ba flag that are
compatible with SMTP.
-bt Runs in address test mode. This mode reads addresses and shows the
steps in parsing; it is used for debugging configuration tables.
-bv Verifies names only. Does not try to collect or deliver a message.
Verify mode is normally used for validating users or mailing lists.
-bz Creates the frozen configuration file. This option is obsolete.
-Cfile
Uses alternate configuration file. The sendmail command refuses to run
as root if an alternate configuration file is specified.
-dX Sets debugging value to X. A useful value is 21.n, where n is any
nonzero integer less than 100. This produces information regarding
address parsing and is typically used with the -bt flag. Higher values
of n produce more verbose information.
-F fullname
Sets the full name of the sender.
-f name
Sets the name of the From: user field (that is, the sender of the
mail). The -f flag can only be used by trusted users (normally root,
daemon, and network) or if the person you are trying to become is the
same as the person you are.
-hN Sets the hop count to N. The hop count is incremented every time the
mail is processed. When it reaches a limit, the mail is returned with
an error message, the victim of an aliasing loop. If not specified,
Received lines in the message are counted. The maximum hop count is
configurable, but defaults to 17 if you do not configure an alternate
value. The default value is acceptable in most installations but you
may want to increase the value if too many messages are being lost
-MMacro Value
Defines Macro to have Value. This option is normally used only from
the sendmail daemon command line.
-n Does not do aliasing or forwarding.
-Ndsn
Set the Delivery Status Notification (DSN) request condition to dsn.
If the remote site understands DSN, it will return a notification based
on the value of dsn. This can be either "never" or a comma-separated
list of:
success Request for notification on successful delivery.
failure Request for notification if a message fails to be delivered.
delay Request for notification if the message is delayed for any
reason.
If the -N flag is omitted, the notification policy is left to the other
site. The default values for dsn are failure and delay. [Version 8 only]
-oXvalue
Sets option X to the specified value. Processing flags specified with
-o are described in the Processing Flags section.
-pprotocol
Set the name of the protocol used to receive the message. This can be a
simple protocol name such as UUCP or a protocol and hostname, such as
UUCP:ucbvax. [Version 8 only]
-q[time]
Processes saved messages in the queue at given intervals. If time is
omitted, processes the queue once. The time command is given as a
tagged number, with s being seconds, m being minutes, h being hours, d
being days, and w being weeks. For example, -q1h30m or -q90m would
both set the time-out to 1 hour and 30 minutes. If the time command is
specified, the sendmail command will run in background mode. This flag
can be used safely with -bd.
-qIsubstr
Limit processed jobs to those containing substr as a substring of the
queue ID. [Version 8 only]
-qRsubstr
Limit processed jobs to those containing substr as a substring of one
of the recipients. [Version 8 only]
-qSsubstr
Limit processed jobs to those containing substr as a substring of the
sender. [Version 8 only]
-rname
An alternate and obsolete form of the -f flag.
-Rret
Defines what to return on a Delivery Status Notification if the message
is bounced. [Version 8 only]
The value of ret can be:
full Return the entire message.
hdrs Return headers only.
-t Reads a message for recipients. The To:, Cc:, and Bcc: lines will be
scanned for recipient addresses. The Bcc: line will be deleted before
transmission. Any addresses in the argument list will be suppressed;
that is, they will not receive copies even if listed in the message
header.
-v Goes into verbose mode. Alias expansions will be announced, and so
forth.
-X logfile
Log all traffic in and out of mailers in the indicated log file. This
should only be used as a last resort for debugging mailer bugs. It will
log a lot of data very quickly.
DESCRIPTION
The sendmail command sends a message to one or more recipients, routing the
message over whatever networks are necessary. The sendmail command does
internetwork forwarding as necessary to deliver the message to the correct
place.
The sendmail command is not intended as a user interface routine. Other
programs provide user-friendly front ends; sendmail is used only to deliver
preformatted messages.
With no flags, sendmail reads its standard input up to an End-of-File or to
a line consisting only of a single . (dot), and sends a copy of the message
found there to all of the addresses listed. It determines the network(s)
to use based on the syntax and contents of the addresses.
Local addresses are looked up in a file and aliased appropriately.
Aliasing can be prevented by preceding the address with a \ (backslash).
Normally the sender is not included in any alias expansions; for example,
if john sends to group, and group includes john in the expansion, then the
letter will not be delivered to john.
DIGITAL UNIX provides /usr/sbin/sendmail.v8 and an older version based upon
Version 5.65 and IDA extensions. By default, /usr/sbin/sendmail is linked
to sendmail Version 8.
For additional information on mail, see the sendmail book by O'Reilly &
Associates.
Processing Option Flags
There are a number of optional sendmail processing flags that can be set.
Normally, these will only be used by a system administrator. Processing
flags can be set either on the command line using the -o flag or in the
configuration file. (Refer to the sendmail.cf reference page for details
on the sendmail.cf file.)
The processing flags are as follows:
Afile
Full pathname to the alias file.
bminblocks
The minimum number of free blocks (bminblocks) needed on the spool
filesystem. [Version 8 only]
BCharacter
Sets the blank substitution character to the character specified in the
Character parameter. The sendmail daemon replaces unquoted spaces in
addresses with Character. The supplied configuration file uses the .
(dot) for Character.
c Causes sendmail to queue messages for that mailer daemon without
sending them if an outgoing mailer is marked as expensive to use. The
queue can be run when costs are lower or when the queue is large enough
to send the message efficiently.
Cn Checkpoint the queue file after n successful deliveries. This avoids
excessive duplicate deliveries when sending to a large mailing list
should the mail delivery be interrupted.
dx Sets the delivery mode to x. Delivery modes are i for interactive
(synchronous) delivery, b for background (asynchronous) delivery, and q
for queue only (that is, actual delivery is done the next time the
queue is run).
D Tries to automatically rebuild the alias database if necessary.
ex Sets error processing to mode x. Valid modes are the following:
e Mails the error message to the user's mailbox, but always exits
with a 0 (zero) exit status (normal return).
m Mails the error message to the user's mailbox.
p Displays the error message on the terminal (default).
q Throws away the error message and returns the exit status only.
w Writes the error message to the terminal or mails it if the user is
not logged in.
If the text of the message is not mailed by modes m or w and if the
sender is a local user, a copy of the message is appended to the
dead.letter file in the sender's home directory.
Fmode
The mode to use when creating temporary files.
f Saves UNIX compatible style From: lines at the front of messages.
G Enables GECOS fuzzy-logic name matching.
The GECOS fields is a field in the /etc/passwd file that usually
contains the user's full name. You can modify this information by
using the chfn routine. If sendmail does not find an exact match for
the user name, the Match-GECOS option tries to match the user name
against names in the /etc/passwd file.
For example, if user Jane Q. Public's user name is jpq, she will
receive mail sent to jane, if she is the only Jane in the /etc/passwd
file. Likewise, if John Doe's username is jd, he will receive mail
sent to doe, if he is the only Doe in the /etc/passwd file.
The sendmail Version 8 command and previous versions of sendmail differ
in how they process GECOS information. If the GECOS option is enabled,
sendmail Version 8 is very stringent; it requires a match on the entire
name. For instance, if the GECOS field for user jd is "John Doe", then
sendmail Version 8 will only work for mail sent to john doe. An older
version of sendmail may work with john doe, john, or doe assuming that
this is the only john (or the only doe) in the file.
gN The default group ID to use when calling mailers.
Hfile
The SMTP help file.
hN Specifies the maximum hop count.
The maximum hop count option specifies the maximum number of machines
that a mail message can be sent to before it is rejected. This limit
is used to help prevent infinite mail loops. The default is 17.
Depending on the size of your mail system, you may require a higher or
lower minimum hop count.
i Does not interpret a . (dot) on a line by itself as a message
terminator. Removes the excess dot inserted by a remote mailer at the
beginning of a line if mail is received through SMTP. In addition, if
receiving mail through SMTP, any dot at the front of a line followed by
another dot is removed. This is the opposite of the action performed
by the X mailer flag.
I Indicate that sendmail should use the Internet domain name server if it
can.
j Send error messages in Multipurpose Internet Mail Extension (MIME)
format. [Version 8 only]
Ktimeout
Set connection cache time out. [Version 8 only]
kN Set connection cache size. [Version 8 only]
Lnumber
Specifies the log level to be the value supplied in the number
argument. Each number includes the activities of all numbers of lesser
value and adds the activity that it represents. Valid levels and the
activities that they represent are as follows:
0 Prevents logging.
1 Logs major problems only.
2 Logs message collections and failed deliveries.
3 Logs successful deliveries.
4 Logs messages deferred (for example, because the host is down).
5 Logs messages that are placed in the queue (normal event).
6 Logs unusual but benign incidents (for example, trying to process a
locked file).
9 Logs the internal queue ID to external message ID mappings (the
default). This can be useful for tracing a message as it travels
between several hosts.
12 Logs messages that are of interest when debugging.
16 Logs verbose information regarding the queue.
m If the sender uses an alias, and that sender is a member of the group
named by the alias, then also send to the sender.
n Validates the right-hand side of alias rewrite rules when the sendmail
daemon performs the newaliases function.
NNetworkName
Applies to versions prior to Version 8. Sets the name of the host
network to NetworkName. The sendmail daemon compares the argument of
an SMTP HELLO command to HostName.NetworkName (value of HostName comes
from the kernel). If these values do not match, it adds the
HostName.NetworkName string to the Received: line in the message so
that messages can be traced accurately.
o If set, this message may have old style headers. If not set, this
message is guaranteed to have new style headers (that is, commas
instead of spaces between addresses). If set, an adaptive algorithm is
used that will correctly determine the header format in most cases.
PAddress
Identifies the person who is to receive a copy of all returned mail.
Qqueuedir
Selects the directory in which to queue messages. The directory will be
created if it does not exist.
rtimeout
The time-out on reads. If none is set, sendmail will wait forever for
a mailer. This flag violates the word (if not the intent) of the SMTP
specification, so the time-out should probably be fairly large.
The sendmail Version 8 command has additional fine-grained control of
timeouts. See the Sendmail Installation and Operation Guide for
additional information. This guide can be accessed from the following
URL:
http://uwsg.ucs.indiana.edu/usail/mail/op/op.html
Sfile
Saves statistics in the named file. Statistics are only collected if
the file exists. This file must be created by the user. The
recommended path for this is /var/adm/sendmail/sendmail.st. Statistics
can be printed out using /usr/sbin/mailstats.
s Always instantiates the queue file, even under circumstances where it
is not strictly necessary. This provides safety against system crashes
during delivery.
Ttime
Sets the time-out on undelivered messages in the queue to the specified
time. After delivery has failed (for example, because of a host being
down) for this amount of time, failed messages will be returned to the
sender. The default in the configuration file is 3 days.
tstz,dtz
Sets the name of the time zone.
uN Sets the default user ID for mailers.
v Runs in verbose mode.
Y The sendmail daemon delivers each message in the mail queue from a
separate process. This option is not required; it can increase system
overhead in this environment.
Aliases Interpretation
In aliases, the first character of a name can be a vertical bar to cause
interpretation of the rest of the name as a command to pipe the mail to.
It may be necessary to quote the name to keep sendmail from suppressing the
blanks from between arguments. For example, a file can contain a common
alias such as:
msgs: "|/usr/bin/msgs -s"
Aliases can also have the syntax :include:filename to ask sendmail to read
the named file for a list of recipients. For example, an alias such as:
poets: :include:/usr/local/lib/poets.list
reads /usr/local/lib/poets.list for the list of addresses making up the
group.
You can also use the Network Information Service (NIS) to distribute
your aliases to other systems.
Exit Status
The sendmail command returns an exit status describing what it did. The
codes are defined in <sysexits.h>:
EX_OK Successful completion on all addresses.
EX_NOUSER
The username was not recognized.
EX_UNAVAILABLE
A catchall meaning necessary resources were not available.
EX_SYNTAX
There is a syntax error in the address.
EX_SOFTWARE
There is an internal software error, including bad arguments.
EX_OSERR There is a temporary operating system error, such as cannot fork.
EX_NOHOST
The hostname was not recognized.
EX_TEMPFAIL
The message could not be sent immediately, but was queued.
Links to sendmail
Three additional commands are links to sendmail:
/usr/sbin/mailq
Prints the contents of the mail queue. This command is the same as
running sendmail with the -bp flag.
/usr/sbin/newaliases
Builds a new copy of the alias database from the
/var/adm/sendmail/aliases file. This command is the same as
running sendmail with the -bi flag.
/usr/sbin/smtpd
Runs sendmail as a daemon. This command is equivalent to invoking
sendmail with the -bd flag.
Mail Addresses
Mail addresses are based on the domain address (Internet) protocol. These
addresses have the form:
user@host.domain
Note that the configuration file provided with sendmail specifies that
blanks in addresses be converted to dots before being transmitted. This
convention follows the Internet mail protocol described in RFC822, but does
not match the Internet mail protocol described in RFC733 (NIC41952). You
can change this setting by setting the OB flag in the sendmail
configuration file (see the sendmail.cf(4) reference page).
A domain is a logical grouping of systems that are connected together by
physical network links. No direct relationship exists between the actual
physical interconnections and the way in which the systems are grouped in
the domain. The domain name identifies a specific domain within a larger
group of domains. The domain name has the format of a tree structure.
Each node (or leaf) on the tree corresponds to a resource set, and each
node can create and contain new domains below it. The actual domain name
of a node is the path from the root of the tree to that node.
For example, if node hera is part of the domain OSF, which is in turn a
subdomain of ORG, a message sent to user geo at that address, uses this
format:
geo@hera.OSF.ORG
The message router (usually sendmail) must determine how to send the
message to its final destination. If the router is at hera, it delivers
the message to user geo. If the router is at another system within the OSF
domain, it corresponds with the name server for that domain to find out how
to deliver the message. If the router is not a part of the OSF domain but
is in a domain that is under the ORG domain, it corresponds with the name
server for the ORG domain to find out how to deliver the message. The
respective name server returns a network address to the router. That
network address determines the actual path that the message takes to its
destination.
The domain address is read from right to left, with each domain in the
address separated from the next domain by a . (dot). This format does not
imply any routing. Thus, although the example is specified as an ORG
address, the message might actually travel by a different route if that
were more convenient or efficient. At one site, the message associated
with the sample address goes directly from the sender to node hera over a
local area network. At another site, it might be sent over a UUCP network
or a combination of other delivery methods.
Normally, the actual routing of a message is handled automatically.
However, you can route the message manually through several specified hosts
to get it to its final destination. An address using intermediate hosts,
called a route address, has the following form:
@hosta,@hostb:user@hostc
Explicitly specifying the message routing with these route addresses, while
supported, is strongly discouraged by RFC 1123. Instead, allow the mail
software (for example sendmail) to handle routing issues.
This address specifies that the message goes first to the remote system
represented by hosta, then to the remote system represented by hostb, and
finally to the remote system represented by hostc. This path is forced
even if there is a more efficient route to hostc.
In some cases you may abbreviate the address rather than entering the
entire domain name. In general, systems in the same domain do not need to
use the full domain name. For example, a user on node zeus.XYZ.COM can
send a message to geo@hera.XYZ.COM by entering only geo@hera because they
are in the same local domain, XYZ.COM.
Other mail address formats exist and the mail routing program (sendmail)
converts most of these other formats to a format that the network routing
system can use. However, if you use the domain address format, the routing
program operates more efficiently.
For example, if sendmail receives an address in the following format:
@host:user
it converts it to the corresponding domain address format:
user@host
Similarly, if sendmail receives an address in the following format:
host!user
the mail routing program routes the message directly to the uucp command.
However, when sending mail via uucp, you must include a route address that
indicates which UUCP host(s) to send the message through to get to the
final destination.
To route messages through the UUCP network, use one of the following domain
address formats. Your choice depends on the way in which the systems at
your site are connected:
1. @system_name.domain_name:uucp-route!user-ID
For example, the address:
@zeus:hera!amy
sends a message to user amy on UUCP host hera by way of system zeus.
The address:
@apollo.802:merlin!lgh
sends a message to user lgh on UUCP host merlin via system apollo
under the local domain 802.
2. uucp-route:!user-ID@system_name.domain_name
In this case, the address:
merlin!arthur!amy@hera.802
sends a message to user amy on system hera under domain 802 via the
UUCP link merlin through arthur.
3. system_name.domain_name:uucp-route:!user-ID@system_namedomain_name
In this example, the address:
@apollo.802:merlin!arthur!amy@hera.802
sends a message to user amy on system hera under domain 802 that first
goes through apollo, the gateway node for domain 802, and then through
the UUCP link merlin through arthur. (Including 802 in this example
is optional because the two domain names are identical.)
4. hosta!hostb!hostc!user
This example is a purely UUCP route address.
zeus!hera!kronos!amy
sends a message to amy on kronos via the UUCP link zeus through hera.
5. @hosta.UUCP:@hostb.UUCP:user@hostc
This example, like the previous one, is a purely UUCP route address.
@zeus.UUCP:@hera.UUCP:amy@kronos.UUCP
sends a message to amy on kronos via the UUCP link zeus through hera.
Your host may also be configured to handle DECnet addresses. Under
DECnet Phase IV, an address is of the form
nodename::username
This is typically converted into a "domain'ized" form, such as
user@nodename.dnet.parent-domain (parent-domain is something such as
dec.com or OSF.ORG that uniquely identifies your company). Similarly,
your host may also handle Phase V type addresses, such as
joe@dec:.nyc.mars.
NOTES
By default, DIGITAL UNIX's sendmail software uses message encoding that
uses 8 bits of each byte. Although 8-bit encoding better supports the full
range of characters in many non-English languages, 8-bit encoding is not
generally recommended because it violates the SMTP protocol used for mail
transmission over a TCP/IP network.
RESTRICTIONS
DIGITAL UNIX software does not support the -bz option.
FILES
/usr/sbin/sendmail
Specifies the command path.
/var/adm/sendmail/sendmail.cf
The configuration file.
/var/adm/sendmail/aliases
The raw data for alias names. Sets the option variable A to
the full pathname of the aliases file
(/var/adm/sendmail/aliases).
/var/adm/sendmail/aliases.pag
This file and the aliases.dir file comprise the database of
alias names.
/var/adm/sendmail/aliases.dir
This file and the aliases.pag file comprise the database of
alias names.
/var/adm/sendmail/sendmail.fc
A frozen configuration.
This option is not supported in DIGITAL UNIX.
/usr/share/lib/sendmail.hf
The help file.
/var/adm/sendmail/sendmail.st
The collected statistics.
/usr/spool/mqueue/*
The mail queue directory.
Except for /usr/sbin/sendmail and /var/adm/sendmail.cf, the previous
pathnames are all specified in the /var/adm/sendmail.cf file, so they may
vary on your system.
/var/run/sendmail.pid
The process id of the daemon.
RELATED INFORMATION
Commands: mail(1), mailx(1), rc0(8)
Functions: syslog(3)
Files: aliases(4), forward(4), sendmail.cf(4)
Specifications: RFC819, RFC821, RFC822