diff -Nur smeserver-vacation-1.1.old/root/usr/local/bin/vacation smeserver-vacation-1.1/root/usr/local/bin/vacation
--- smeserver-vacation-1.1.old/root/usr/local/bin/vacation	2017-01-16 16:44:03.999000000 -0500
+++ smeserver-vacation-1.1/root/usr/local/bin/vacation	2017-01-16 16:48:09.939000000 -0500
@@ -493,6 +493,8 @@
 	exit(0) if ($no_msg_no_reply);
     }
 
+    my $type = ($vacation_msg =~ m/<html/ && $vacation_msg =~ m/<\/html>/  ) ? 'html':'plain';
+
     $vacation_msg =~ s/\$SUBJECT/$subject/g;
 
     open(MAILPROG, "| $mailprog");
@@ -500,7 +502,7 @@
     print MAILPROG << "EOF";
 To: $sender
 Precedence: junk
-Content-Type: text/plain; charset="UTF-8"
+Content-Type: text/$type; charset="UTF-8"
 EOF
 
     print MAILPROG $vacation_msg;