Mail in_reply_to field is Null in Envelope Index

Question

I am trying to pull some data from the sqlite database Mail uses. However, the in_reply_to field of the messages table is NULL for every value.
set databasePath to POSIX path of (path to library folder from user domain as text) & "Mail/V2/MailData/Envelope Index"
set theReply to (do shell script "sqlite3 " & quoted form of databasePath & " \"SELECT DISTINCT in_reply_to from messages;\"")
However, I can extract the value of the header with something like this:
tell application "Mail"
          set aMessage to first item of (get selection)
          try
                    set inReplyTo to extract address from (content of aMessage's header "in-reply-to")
          on error
                    set inReplyTo to "NULL"
          end try
end tell
Where can I find the value of in_reply_to field within the Envelope Index database?

Answer 1

I found the answer in
http://www.entourage.mvps.org/faq_topic/reply.html#reply4
thanks to the Microsoft news server...