Index: mail_handler.rb
===================================================================
--- mail_handler.rb	(revision 12119)
+++ mail_handler.rb	(working copy)
@@ -139,6 +139,7 @@
   MESSAGE_ID_RE = %r{^<?redmine\.([a-z0-9_]+)\-(\d+)\.\d+(\.[a-f0-9]+)?@}
   ISSUE_REPLY_SUBJECT_RE = %r{\[[^\]]*#(\d+)\]}
   MESSAGE_REPLY_SUBJECT_RE = %r{\[[^\]]*msg(\d+)\]}
+  ISSUE_REPLY_MATCH_ISSUE_SUBJECT_RE = %r{^Re: (.+)$}
 
   def dispatch
     headers = [email.in_reply_to, email.references].flatten.compact
@@ -155,6 +156,8 @@
       receive_issue_reply(m[1].to_i)
     elsif m = subject.match(MESSAGE_REPLY_SUBJECT_RE)
       receive_message_reply(m[1].to_i)
+    elsif m = subject.match(ISSUE_REPLY_MATCH_ISSUE_SUBJECT_RE)
+      receive_issue_reply_subject(m[1].to_s, m[0].to_s)
     else
       dispatch_to_default
     end
@@ -230,6 +233,17 @@
     journal
   end
 
+  # Adds a note to an existing issue, matched by subject
+  def receive_issue_reply_subject(issue_subject, re_issue_subject)
+    if issue = Issue.find_last_by_subject(issue_subject)
+      receive_issue_reply(issue.id)
+    elsif issue = Issue.find_last_by_subject(re_issue_subject)
+      receive_issue_reply(issue.id)
+    else
+      receive_issue
+    end
+  end
+
   # Reply will be added to the issue
   def receive_journal_reply(journal_id)
     journal = Journal.find_by_id(journal_id)