archive file name

I seem to remember there used to be a mail header on SmartList out-going 
mails to show the path/file_name (usually a number) of the archived copy 
of the mail, but cannot find how to make it appear from all online FAQs 
and other available documentations. I may have overlooked somewhere?

My actual need is to bring the archive path/file information into the 
mail body, with an inserted line saying how to access an online copy if 
the mail body contains truncated URL or in bad formats. Any hint to get 
that info would be much appreciated.

Thanks!
Zhiliang

ps: This list has been quiet. It appears there are not many enthusiastic 
new users any more?