(   echo To: email@hidden.com;   echo From: emailer@hidden.com;   echo "Content-Type: text/html; ";   echo Subject: Test Emails;   echo;   cat index.html; ) | sendmail -t -v

Outputs: 

LOG: MAIN
  cwd=/var/spool/exim 4 args: /usr/sbin/exim -v -Mc 1WruKt-0001VR-Fv
delivering 1WruKt-0001VR-Fv
LOG: MAIN
  => :blackhole: <email@hidden.com> R=virtual_aliases
LOG: MAIN
  Completed