diff -Nur qpsmtpd-0.96.old/plugins/headers qpsmtpd-0.96/plugins/headers
--- qpsmtpd-0.96.old/plugins/headers	2016-02-16 17:52:02.000000000 -0500
+++ qpsmtpd-0.96/plugins/headers	2017-03-08 11:59:48.411000000 -0500
@@ -18,6 +18,8 @@
 
 If the remote IP is whitelisted, header validation is skipped.
 
+As per March 2017 it has been reported some well known senders are putting multiple Message-Id. As a result we removed Message-Id from the singular_headers array. See https://bugs.contribs.org/show_bug.cgi?id=9773
+
 =head1 CONFIGURATION
 
 The following optional settings exist:
@@ -106,8 +108,8 @@
 
 #my @should_headers   = qw/ Message-ID /;
 my @singular_headers = qw/ Date From Sender Reply-To To Cc Bcc
-  Message-Id In-Reply-To References
-  Subject /;
+  In-Reply-To References
+  Subject /; # <- to be RFC 5322 complient add Message-Id here
 
 sub register {
     my ($self, $qp) = (shift, shift);