I need some clarification of what 'reply-hook' does please

[Chris Green]

When the documentation says "reply-hook is matched against the message
you are replying to," does that mean I can use it to hook all messages
sent to just one of my 'alternates' addresses?

I want to execute an action only when I am replying to an E-Mail which
has been sent to 'cl at isbd.net' and not one sent to any of my other
addresses.  Will reply-hook do this for me?

-- 
Chris Green