File Formats aliases(4)
NAME
aliases, addresses, forward - addresses and aliases for
sendmail
SYNOPSIS
/etc/mail/aliases
/etc/mail/aliases.db
/etc/mail/aliases.dir
/etc/mail/aliases.pag
~/.forward
DESCRIPTION
These files contain mail addresses or aliases, recognized by
sendmail(1M) for the local host:
/etc/passwd
Mail addresses (usernames) of local users.
/etc/mail/aliases
Aliases for the local host, in ASCI format. Root can
edit this file to add, update, or delete local mail
aliases.
/etc/mail/aliases.{dir , pag}
The aliasing information from /etc/mail/aliases, in
binary ndbm(3C) format for use by sendmail(1M). The pro-
gram newaliases(1M) maintains these files.
/etc/mail/aliases.db
The aliasing information from /etc/mail/aliases, in
binary, Berkeley DataBase format for use by
sendmail(1M). The program maintains these files.
Depending on the configuration of the AliasFile option
in /etc/mail/sendmail.cf, either the single file
aliases.db or the pair of files aliases.{dir, pag} is
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File Formats aliases(4)
generated by newaliases(1M). As shipped with Solaris,
sendmail(1M) supports both formats. If neither is speci-
fied, the Berkeley DataBase format which generates the
single .db file is used.
~/.forward
Addresses to which a user's mail is forwarded (see
Automatic Forwarding).
In addition, the NIS name services aliases map mail.aliases,
and the NIS] mailaliases table, both contain addresses and
aliases available for use across the network.
Addresses
As distributed, sendmail(1M) supports the following types of
addresses:
Local Usernames
username
Each local username is listed in the local host's
/etc/passwd file.
Local Filenames
pathname
Messages addressed to the absolute pathname of a file are
appended to that file.
Commands
command
If the first character of the address is a vertical bar (),
sendmail(1M) pipes the message to the standard input of the
command the bar precedes.
Internet-standard Addresses
username@domain
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If domain does not contain any `.' (dots), then it is inter-
preted as the name of a host in the current domain. Other-
wise, the message is passed to a mailhost that determines
how to get to the specified domain. Domains are divided into
subdomains separated by dots, with the top-level domain on
the right.
For example, the full address of John Smith could be:
js@jsmachine.Podunk-U.EDU
if he uses the machine named jsmachine at Podunk University.
uucp Addresses
... [host!] host!username
These are sometimes mistakenly referred to as ``Usenet''
addresses. uucp(1C) provides links to numerous sites
throughout the world for the remote copying of files.
Other site-specific forms of addressing can be added by cus-
tomizing the sendmail.cf configuration file. See
sendmail(1M) for details. Standard addresses are recom-
mended.
Aliases
Local Aliases
/etc/mail/aliases is formatted as a series of lines of the
form
aliasname:address[, address]
aliasname is the name of the alias or alias group, and
address is the address of a recipient in the group. Aliases
can be nested. That is, an address can be the name of
another alias group. Because of the way sendmail(1M) per-
forms mapping from upper-case to lower-case, an address that
is the name of another alias group must not contain any
upper-case letters.
Lines beginning with white space are treated as continuation
lines for the preceding alias. Lines beginning with # are
comments.
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Special Aliases
An alias of the form:
owner-aliasname : address
sendmail directs error-messages resulting from mail to
aliasname to address, instead of back to the person who sent
the message. sendmail rewrites the SMTP envelope sender to
match this, so owner-aliasname should always point to
alias-request, and alias-request should point to the owner's
actual address:
owner-aliasname: aliasname-request
aliasname-request address
An alias of the form:
aliasname: :include:pathname
with colons as shown, adds the recipients listed in the file
pathname to the aliasname alias. This allows a private list
to be maintained separately from the aliases file.
NIS and NIS] Domain Aliases
The aliases file on the master NIS server is used for the
mail.aliases NIS map, which can be made available to every
NIS client. The mailaliases table serves the same purpose
on a NIS] server. Thus, the /etc/mail/aliases* files on the
various hosts in a network will one day be obsolete.
Domain-wide aliases should ultimately be resolved into user-
names on specific hosts. For example, if the following were
in the domain-wide alias file:
jsmith:js@jsmachine
then any NIS or NIS] client could just mail to jsmith and
not have to remember the machine and username for John
Smith.
If a NIS or NIS] alias does not resolve to an address with a
specific host, then the name of the NIS or NIS] domain is
used. There should be an alias of the domain name for a host
in this case.
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For example, the alias:
jsmith:root
sends mail on a NIS or NIS] client to root@podunk-u if the
name of the NIS or NIS] domain is podunk-u.
Automatic Forwarding
When an alias (or address) is resolved to the name of a user
on the local host, sendmail(1M) checks for a ~/.forward
file, owned by the intended recipient, in that user's home
directory, and with universal read access. This file can
contain one or more addresses or aliases as described above,
each of which is sent a copy of the user's mail.
Care must be taken to avoid creating addressing loops in the
~/.forward file. When forwarding mail between machines, be
sure that the destination machine does not return the mail
to the sender through the operation of any NIS aliases. Oth-
erwise, copies of the message may "bounce." Usually, the
solution is to change the NIS alias to direct mail to the
proper destination.
A backslash before a username inhibits further aliasing. For
instance, to invoke the vacation program, user js creates a
~/.forward file that contains the line:
\js, "/usr/ucb/vacation js"
so that one copy of the message is sent to the user, and
another is piped into the vacation program.
The ~/.forward file can be used to specify special "per
user" extensions by creating a .forward]extension file in
the home directory. For example, with an address like
jsmith]jerry@jsmachine, the sendmail(1M) utility recognizes
everything before the "]" as the actual username (jsmith)
and everything after it, up to the "@" symbol, as the exten-
sion (jerry) which is passed to the mail delivery agent for
local use.
The default value of the ForwardPath processing option in
sendmail(1M) is:
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File Formats aliases(4)
O ForwardPath=$z/.forward.$w]$h:$z/.forward]$h:$z/.forward.$w:$z \
/.forward
where $z is the macro for the user's home directory, $w is
the macro for the local machine name and $h is the exten-
sion. For example, for mail using the address,
jsmith]jerry@jsmachine, the sendmail(1M) utility checks each
of the four following file names, in the order given, to see
if it exists and if it has "safe" permissions, that is, that
neither the file nor any of its parent directories are
group- or world-writable:
~jsmith/.forward.jsmachine]jerry
~jsmith/.forward]jerry
~jsmith/.forward.jsmachine
~jsmith/.forward
The first file that meets the conditions is used to forward
the mail, that is, all the entries in that file receive a
copy of the mail. The search is then stopped.
FILES
/etc/passwd Password file
/etc/nsswitch.conf Name service switch configuration
file
/etc/mail/aliases Mail aliases file (ascii)
/etc/mail/aliases.db Database of mail aliases (binary)
/etc/mail/aliases.dir Database of mail aliases (binary)
/etc/mail/aliases.pag Database of mail aliases (binary)
/etc/mail/sendmail.cf sendmail configuration file
~/.forward Forwarding information file
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File Formats aliases(4)
ATRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
ATRIBUTE TYPE ATRIBUTE VALUE
Availability SUNWsndmr
SEE ALSO
passwd(1), uucp(1C), vacation(1), newaliases(1M),
sendmail(1M), ndbm(3C), getusershell(3C), passwd(4),
shells(4), attributes(5)
NOTES
Because of restrictions in ndbm(3C), a single alias cannot
contain more than about 1000 characters (if this format is
used). The Berkeley DataBase format does not have any such
restriction. Nested aliases can be used to circumvent this
limit.
For aliases which result in piping to a program or con-
catenating a file, the shell of the controlling user must be
allowed. Which shells are and are not allowed are determined
by getusershell(3C).
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