Solaris

 
mailx -vvv -s "test" xxx_xxxh@xxx.com < /dev/null

:/# mailx -vvv -s "test from zone" xxxx@xxx.com < /dev/null
xxxx@xxx.com... Connecting to [127.0.0.1] via relay...
xxxx@xxx.com... Deferred: Connection refused by [127.0.0.1]

:/# svcs -xv
svc:/application/print/server:default (LP print server)
 State: disabled since Tue Aug 30 02:24:56 2011
Reason: Disabled by an administrator.
   See: http://sun.com/msg/SMF-8000-05
   See: man -M /usr/share/man -s 1M lpsched
Impact: 2 dependent services are not running:
        svc:/application/print/rfc1179:default
        svc:/application/print/ipp-listener:default
svc:/system/pkgserv:default (Flush package command database to disk (see pkgadm(1m)).)
 State: offline since Tue Aug 30 02:24:59 2011
Reason: Dependency file://localhost/usr/sadm/install/bin/pkgserv is absent.
   See: http://sun.com/msg/SMF-8000-E2
Impact: This service is not running.
svc:/system/patchchk:default (Launcher for Automatic Patching services)
 State: maintenance since Tue Aug 30 02:24:59 2011
Reason: Start method failed repeatedly, last exited with status 1.
   See: http://sun.com/msg/SMF-8000-KS
   See: /var/svc/log/system-patchchk:default.log
Impact: This service is not running.
:/# ls -l /usr/sadm/install/bin/pkgserv
/usr/sadm/install/bin/pkgserv: No such file or directory

:/root# svcs -xv
svc:/application/management/sunmcdatabase:default (SunMC database service)
 State: maintenance since Tue Aug 30 02:17:40 2011
Reason: Start method exited with $SMF_EXIT_ERR_FATAL.
   See: http://sun.com/msg/SMF-8000-KS
   See: /var/svc/log/application-management-sunmcdatabase:default.log
Impact: 1 dependent service is not running:
        svc:/application/management/sunmctopology:default

 
grep mail /etc/hosts
grep hosts /etc/nsswitch.conf

:/# grep localhost /etc/hosts
127.0.0.1       localhost
::1     localhost
:/# grep mail /etc/hosts
:/# grep hosts /etc/nsswitch.conf
# DNS for hosts lookups, otherwise it does not use any other naming service.
# "hosts:" and "services:" in this file are used only if the
hosts:      dns files
# before searching the hosts databases.
:/#

blockedcontent       blockedcontent      mailhost

mailx -vvv -s "test from zone" xxxx@xxx.com < /dev/null