While ssoma now documents it uses the first Message-ID, they
are confusing and could be a sign of a broken mail software,
and broken mail software is often a sign of spam...
ref: http://public-inbox.org/meta/
20160421221128.4910-1-e@80x24.org/
sub precheck {
my ($klass, $filter, $address) = @_;
my Email::Simple $simple = $filter->simple;
- my $mid = $simple->header("Message-ID");
+ my @mid = $simple->header('Message-ID');
+ return 0 if scalar(@mid) != 1;
+ my $mid = $mid[0];
return 0 if (length($mid) > MAX_MID_SIZE);
return 0 unless usable_str(length('<m@h>'), $mid) && $mid =~ /\@/;
return 0 unless usable_str(length('u@h'), $filter->from);