[imp] Direct link to a message

[Iikku Mattila]

Hi,
I have exactly the same kind of question canobi had ~three years ago, 
seen at
http://marc.info/?l=imp&m=113292496331946&w=2

In short, I get the message number as used by imap from 
javax.mail.Message and would like
to use that in creating a link to imp, something like 
/message.php?mailbox=INBOX&index=40
Alternatively it'd be nice to know how to create the index as used by 
imp, as this clearly isn't the
same as used by imap. Any ideas?

Iikku