Solaris

# mailx -v -s "Test from host01f" User_One@ABC.com < /dev/null
# User_One@ABC.com... Connecting to [127.0.0.1] via relay...
220 host01f.nam.int.local ESMTP Sendmail 8.14.9+Sun/8.14.9; Mon, 16 May 2016 20:52:34 -0500 (CDT)
>>> EHLO host01f.nam.int.local
250-host01f.nam.int.local Hello localhost [127.0.0.1], pleased to meet you
250-ENHANCEDSTATUSCODES
250-PIPELINING
250-EXPN
250-VERB
250-8BITMIME
250-SIZE
250-DSN
250-ETRN
250-DELIVERBY
250 HELP
>>> VERB
250 2.0.0 Verbose mode
>>> MAIL From:<user1@host01f.nam.int.local> SIZE=71
250 2.1.0 <user1@host01f.nam.int.local>... Sender ok
>>> RCPT To:<User_One@ABC.com>
>>> DATA
250 2.1.5 <User_One@ABC.com>... Recipient ok
354 Enter mail, end with "." on a line by itself
>>> .
050 <User_One@ABC.com>... Connecting to smtp.ins.ABC.com. via esmtp...
050 <User_One@ABC.com>... Connecting to mailhost.nam.int.local via esmtp...
050 <User_One@ABC.com>... Connecting to smtp2.ins.ABC.com. via esmtp...
050 <User_One@ABC.com>... Deferred: Name server: mailhost.nam.int.local: host name lookup failure <<<<<<<<< Failure
250 2.0.0 u4H1qY6N028772 Message accepted for delivery
User_One@ABC.com... Sent (u4H1qY6N028772 Message accepted for delivery)
Closing connection to [127.0.0.1]
>>> QUIT
221 2.0.0 host01f.nam.int.local closing connection

#

May 16 17:09:40 host01f sendmail[28782]: [ID 801593 mail.info] u4GM9e3L028782: from=<user1@host01f.nam.int.local>, size=374, class=0, nrcpts=1, 

msgid=<201605162209.u4GM9ewi028781@host01f.nam.int.local>, proto=ESMTP, daemon=MTA, relay=localhost [127.0.0.1]
May 16 17:09:41 host01f sendmail[28782]: [ID 801593 mail.info] u4GM9e3L028782: to=<User_One@ABC.com>, ctladdr=<user1@host01f.nam.int.local> (63184/426), 

delay=00:00:01, xdelay=00:00:00, mailer=esmtp, pri=30374, relay=mailhost.nam.int.local, dsn=4.0.0, stat=Deferred: Name server: mailhost.nam.int.local: host name lookup 

failure
May 16 17:09:41 host01f sendmail[28781]: [ID 801593 mail.info] u4GM9ewi028781: to=User_One@ABC.com, ctladdr=user1 (63184/426), delay=00:00:01, xdelay=00:00:01, 

mailer=relay, pri=30073, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (u4GM9e3L028782 Message accepted for delivery)
May 16 17:20:37 host01f sendmail[2833]: [ID 801593 mail.info] u4GM9e3L028782: to=<User_One@ABC.com>, ctladdr=<user1@host01f.nam.int.local> (63184/426), 

delay=00:10:57, xdelay=00:00:01, mailer=esmtp, pri=120374, relay=mailhost.nam.int.local, dsn=4.0.0, stat=Deferred: Name server: mailhost.nam.int.local: host name 

lookup failure
May 16 17:35:37 host01f sendmail[8249]: [ID 801593 mail.info] u4GM9e3L028782: to=<User_One@ABC.com>, ctladdr=<user1@host01f.nam.int.local> (63184/426), 

delay=00:25:57, xdelay=00:00:01, mailer=esmtp, pri=210374, relay=mailhost.nam.int.local, dsn=4.0.0, stat=Deferred: Name server: mailhost.nam.int.local: host name 

lookup failure
May 16 17:50:37 host01f sendmail[13638]: [ID 801593 mail.info] u4GM9e3L028782: to=<User_One@ABC.com>, ctladdr=<user1@host01f.nam.int.local> (63184/426), 

delay=00:40:57, xdelay=00:00:01, mailer=esmtp, pri=300374, relay=mailhost.nam.int.local, dsn=4.0.0, stat=Deferred: Name server: mailhost.nam.int.local: host name 

lookup failure
May 16 17:54:21 host01f sendmail[14784]: [ID 702911 mail.warning] gethostbyaddr(192.168.224.2) failed: 1

# /usr/lib/sendmail -d0.4 < /dev/null
Version 8.14.9+Sun
 Compiled with: DNSMAP LDAPMAP LOG MAP_REGEX MATCHGECOS MILTER MIME7TO8
                MIME8TO7 NAMED_BIND NDBM NETINET NETINET6 NETUNIX NEWDB NIS
                NISPLUS PIPELINING SCANF STARTTLS TCPWRAPPERS USERDB
                USE_LDAP_INIT XDEBUG
Canonical name: host01f.nam.int.local
 UUCP nodename: host01f
        a.k.a.: [10.141.19.21]

============ SYSTEM IDENTITY (after readcf) ============
      (short domain name) $w = host01f
  (canonical domain name) $j = host01f.nam.int.local
         (subdomain name) $m = nam.int.local
              (node name) $k = host01f
========================================================

Recipient names must be specified
#
# grep DS sendmail.cf
DS
# Return-Receipt-To: header implies DSN request
# DHParameters (only required if DSA/DH is used)
#
# grep Fallback sendmail.cf
#O FallbackMXhost=fall.back.host.net
O FallbackSmartHost=mailhost$?m.$m$.
#
# grep MTAHost submit.cf
D{MTAHost}[127.0.0.1]
R$* < @ $+ > $*         $#relay $@ ${MTAHost} $: $1 < @ $2 > $3
R$+ :: $+               $#relay $@ ${MTAHost} $: $1 :: $2
R$*                     $#relay $@ ${MTAHost} $: $1 < @ $j >
#
# grep DS submit.cf
DS
# Return-Receipt-To: header implies DSN request
# DHParameters (only required if DSA/DH is used)
#