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aliascheck(1)		      Mail Avenger 0.8.4		 aliascheck(1)

NAME
       aliascheck - check for existence	of mail	alias

SYNOPSIS
       aliascheck [--nopwd] name [alias-file]

       aliascheck --map	[--case] name map-file

       aliascheck --qmail [--nopwd] name [alias-user]

DESCRIPTION
       aliascheck checks whether name is a valid email alias or	a user in the
       password	file.  It converts name	to lower-case before performing	any of
       the checks.  If the alias or user exists, aliascheck exits with status
       0 and outputs what the address resolves to.  If the alias does not
       exist, aliascheck exits with status 1.  If aliascheck cannot determine
       the validity of name because of some system error, it exits with	status
       2.

       aliascheck can run in three different modes--sendmail alias mode	(the
       default), sendmail map mode, and	qmail mode.  In	sendmail alias mode
       the second argument, alias-file,	is the name of the sendmail alias
       file, typically /etc/mail/aliases.db.  If no second argument is
       supplied, aliascheck first checks for the existence of
       /etc/mail/aliases.db, then for the existence of /etc/aliases.db,	then
       finally exits with status 2 if neither file exists.  When an alias is
       found, aliascheck outputs the value of that alias in the	alias
       database.

       When aliascheck is invoked with --map, it looks up name in map-file,
       which should be a database created with sendmail's makemap(8) utility.
       Note that maps have a slightly different	and incompatible format	from
       that of alias files.  Use the --case argument to	prevent	name from
       being folded to lower-case before it is looked up in the	database.
       Note that --map implies the --nopwd option.

       When aliascheck is given	the argument --qmail, it runs in qmail mode.
       In this case, the second	argument, alias-user, specifies	the user under
       which qmail processes mail aliases.  aliascheck will check this user's
       home directory for files	named .qmail-XXX for various appropriate
       suffixes	XXX.  On success, it outputs the full pathname of the
       appropriate file.

       If aliascheck cannot find an alias, it also checks the password file,
       and exits 0 if it can find name there.  If name is found, aliascheck
       also outputs name (in lower-case) to standard output before exiting.
       (This is	useful for Mail	Avenger, because asmtpd	does not recognize
       users with invalid shells or UID	0, while MTAs typically	do.)  To
       suppress	password file checking,	supply the --nopwd argument to
       aliascheck.

EXAMPLES
       If you are using	Mail Avenger in	conjunction with a sendmail
       installation, you might want to put the following code in your
       /etc/avenger/unknown file to reject mail	for unknown users who do not
       show up in the alias file.

	   aliascheck "$RECIPIENT_LOCAL" /etc/mail/aliases.db >	/dev/null
	   case	"$?" in
	       0)
		   # Fall through to default checks
		   ;;
	       1)
		   reject unknown user
		   ;;
	       *)
		   # Probably safest to	do nothing, but	could also
		   # defer the mail with the following command:
		   #
		   #defer Temporary error processing alias file
		   ;;
	   esac

       If you have qmail instead of sendmail, assuming the qmail alias user is
       called "alias", you would change	the first line in the previous example
       to:

	   aliascheck --qmail "$RECIPIENT_LOCAL" alias > /dev/null

FILES
       /etc/avenger/unknown
	   Mail	Avenger	rules for local	email addresses	that do	not correspond
	   to local users, or correspond to local users	without	valid shells,
	   or local users with uid 0 (i.e., root).  Note the location may be
	   different if	you set	EtcDir in your asmtpd.conf file.

       /etc/mail/aliases.db
       /etc/aliases.db
	   Default locations of	sendmail alias file

       /etc/mail/virtusertable.db
	   Default location of the sendmail virtual user table map, when this
	   feature is in use.

       ~alias/.qmail-*
	   Default locations of	qmail alias files

       /etc/password
	   System password file.  (Note, however, that aliascheck uses the
	   getpwnam function, and will thus be compatible with schemes such as
	   NIS that do not keep	all users in the local password	file.)

SEE ALSO
       avenger(1), asmtpd.conf(5), makemap(8),

       The Mail	Avenger	home page: <http://www.mailavenger.org/>.

BUGS
       aliascheck doesn't necessarily know how to parse	the particular
       database	format your sendmail installation uses for aliases.  Make sure
       you test	it before using	it in an avenger script.

       In some sendmail	installations, the alias database is not world
       readable, which can obviously prevent aliascheck	from working properly
       if run under the	wrong user identity (such as the AvengerUser).

       It is quite possible for	aliascheck to return a system error (exit code
       2), particularly	if you run it while you	are rebuilding a large alias
       database.  (aliascheck checks for the existence of special key "@" in
       the database.)  Make sure you differentiate between error code 1	(no
       user) and error code 2 (system error).

       aliascheck may not do the right thing if	you installed qmail with conf-
       break set to a character	other than "-".

       Remember	that aliascheck	does not read your qmail users/assign or
       users/cdb files--it only	checks for .qmail files	in the alias user's
       home directory.

AUTHOR
       David Mazieres

Mail Avenger 0.8.4		  2013-07-13			 aliascheck(1)

NAME | SYNOPSIS | DESCRIPTION | EXAMPLES | FILES | SEE ALSO | BUGS | AUTHOR

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