v2: improve deduplication checks

First off, decode text portions of messages since some archived
mail I got was converted from quoted-printable or base-64 to
8bit by the original recipient.  Attempting to merge them with
my own archives (which had no conversion done) led to
unnecessary duplicates showing up.

Then, normalize CRLF line endings in text portions to LF.

In the headers, we relax the content_id hashing to ignore quotes
and lower-case domain names in To, Cc, and From headers since
some mail processors will alter them.

Finally, I've discovered Email::MIME->new($mime->as_string)
does not always round-trip reliably, so we calculate the
content_id twice on user-supplied messages.

1 files changed, 10 insertions, 0 deletions

diff --git a/t/content_id.t b/t/content_id.t
index adcdb6c1..01ce65e5 100644
--- a/t/content_id.t
+++ b/t/content_id.t
@@ -22,4 +22,14 @@ my $orig = content_id($mime);
 my $reload = content_id(Email::MIME->new($mime->as_string));
 is($orig, $reload, 'content_id matches after serialization');
 
+foreach my $h (qw(From To Cc)) {
+        my $n = '"Quoted N\'Ame" <foo@EXAMPLE.com>';
+        $mime->header_str_set($h, "$n");
+        my $q = content_id($mime);
+        is($n, $mime->header($h), "content_id does not mutate $h:");
+        $mime->header_str_set($h, 'Quoted N\'Ame <foo@example.com>');
+        my $nq = content_id($mime);
+        is($nq, $q, "quotes ignored in $h:");
+}
+
 done_testing();