Send message to part of website (4)
I believe the answer is:
page
I believe this is a double definition.
'send message' is the first definition.
'part of website' is the second definition.
'to' is the link.
(Other definitions for page that I've seen before include "Young male attendant" , "Errand boy at hotel, club etc" , "contact" , "Leaf; call over PA system" , "a significant bit of history?" .)