Index: cvsspam.rb
===================================================================
RCS file: /var/lib/cvs/cvsspam/cvsspam.rb,v
retrieving revision 1.69
diff -u -r1.69 cvsspam.rb
--- cvsspam.rb	13 May 2005 20:06:55 -0000	1.69
+++ cvsspam.rb	14 May 2005 10:53:33 -0000
@@ -1235,6 +1235,7 @@
 $debug = false
 $recipients = Array.new
 $sendmail_prog = "/usr/sbin/sendmail"
+$hostname = ENV['HOSTNAME'] || 'localhost'
 $no_removed_file_diff = false
 $no_added_file_diff = false
 $no_diff = false
@@ -1748,7 +1749,7 @@
       from = EmailAddress.new(ENV['USER'] || ENV['USERNAME'] || 'cvsspam')
     end  
     unless from.address =~ /@/
-      from.address = "#{from.address}@#{ENV['HOSTNAME']||'localhost'}"
+      from.address = "#{from.address}@#{$hostname}"
     end
     smtp = Net::SMTP.new(@smtp_host)
     blah("connecting to '#{@smtp_host}'")
@@ -1764,6 +1765,40 @@
   end
 end
 
+
+def make_msg_id(localpart, hostpart)
+  "<cvsspam-#{localpart}@#{hostpart}>"
+end
+
+
+# replaces control characters, and a selection of other characters that
+# may not appear unquoted in an RFC822 'word', with underscores.  (It
+# doesn't actually zap '.' though.)
+def zap_header_special_chars(text)
+  text.gsub(/<>()\[\]@,;:\\[\000-\037\177]/, "_")
+end
+
+
+# Mail clients will try to 'thread' together a conversation over
+# several email messages by inspecting the In-Reply-To and References headers,
+# which should refer to previous emails in the conversation by mentioning
+# the value of the previous message's Message-Id header.  This function invents
+# values for these headers so that, in the special case where a *single* file
+# is committed to repeatedly, the emails giving notification of these commits
+# can be threaded together automatically by the mail client.
+def inject_threading_headers(mail)
+  return unless $fileEntries.length == 1
+  file = $fileEntries[0]
+  name = zap_header_special_chars(file.path)
+  unless file.fromVer == "NONE"
+    mail.header("References", make_msg_id("#{name}.#{file.fromVer}", $hostname))
+  end
+  unless file.toVer == "NONE"
+    mail.header("Message-ID", make_msg_id("#{name}.#{file.toVer}", $hostname))
+  end
+end
+
+
 if $smtp_host
   require 'net/smtp'
   mailer = SMTPMailer.new($smtp_host)
@@ -1775,6 +1810,7 @@
 
 mailer.send($from_address, $recipients) do |mail|
   mail.header("Subject", mailSubject)
+  inject_threading_headers(mail)
   mail.header("MIME-Version", "1.0")
   mail.header("Content-Type", "text/html" + ($charset.nil? ? "" : "; charset=\"#{$charset}\""))
   if ENV['REMOTE_HOST']