Sendmail not working with relay, files queuing in /var/spool/mailqueue

Issue

• Sendmail is not using relay server while forwarding mail with smarthost set up

• Queued messages in /var/log/maillog:

  Aug 10 10:11:43 hostname sendmail[46050]: t7AHA43o046050: from=<root@hostname.example.com>, size=505, class=0, nrcpts=1, msgid=<201508101710>, proto=ESMTP, daemon=MTA, relay=localhost.local [127.0.0.1] 
  Aug 10 10:11:43 hostname sendmail[46050]: t7AHA43o046050: to=<user@example.com>, delay=00:00:00, mailer=relay, pri=30505, dsn=4.4.3, stat=queued  
  Aug 10 10:11:43 hostname sendmail[46049]: t7AHA4Lx046049: to=user@example.com, ctladdr=root (0/0), delay=00:01:39, xdelay=00:01:39, mailer=relay, pri=30219, relay=[127.0.0.1] [127.0.0.1],                       dsn=2.0.0,stat=Sent   (t7AHA43o046050 Message accepted for delivery)