Bug 31314 : Support for "In-Reply-To" header in emails

Bugzilla/BugMail.pm

@@ -46,6 +46,13 @@ my $last_changed;
 
 my @excludedAddresses = ();
 
+my $sitespec = '@'.Param('urlbase');
+$sitespec =~ s/:\/\//\./; # Make the protocol look like part of the domain
+$sitespec =~ s/^([^:\/]+):(\d+)/$1/; # Remove a port number, to relocate
+if ($2) {
+    $sitespec = "-$2$sitespec"; # Put the port number back in, before the '@'
+}
+
 # disable email flag for offline debugging work
 my $enableSendMail = 1;
 
@@ -854,6 +861,11 @@ sub NewProcessOnePerson ($$$$$$$$$$$$$) {
     $substs{"reasonsheader"} = join(" ", @reasons);
     $substs{"reasonsbody"} = $reasonsbody;
     $substs{"space"} = " ";
+    if ($isnew) {
+        $substs{'threadingmarker'} = "Message-ID: <bug-$id-$userid$sitespec>";
+    } else {
+        $substs{'threadingmarker'} = "In-Reply-To: <bug-$id-$userid$sitespec>";
+    }
     
     my $template = Param("newchangedmail");
     

defparams.pl

@@ -719,13 +719,18 @@ To use the wonders of Bugzilla, you can use the following:
            'getting the email, suitable for use in an email header (such ' .
            'as X-Bugzilla-Reason). %reasonsbody% is replaced by text that ' .
            'explains why the user is getting the email in more user ' .
-           'friendly text than %reasonsheader%. %<i>anythingelse</i>% gets ' .
+           'friendly text than %reasonsheader%. ' .
+           '%threadingmarker% will become either a Message-ID line (for ' .
+           'new-bug messages) or a In-Reply-To line (for bug-change ' .
+           'messages). ' .
+           '%<i>anythingelse</i>% gets ' .
            'replaced by the definition of that parameter (as defined on ' .
            'this page).',
    type => 'l',
    default => 'From: bugzilla-daemon
 To: %to%
 Subject: [Bug %bugid%] %neworchanged%%summary%
+%threadingmarker%
 X-Bugzilla-Reason: %reasonsheader%
 
 %urlbase%show_bug.cgi?id=%bugid%