php question for any techies out there.

[Mark]

I want to show a message at the top of a page depending on where a user has arrived from. To clarifiy: I go to www.sitey.co.uk, this has a redirect in place that goes to site X (sitex.co.uk), site X recognises that I've come from site Y and shows a message.

The rule will be: If person arrives at website X having been redirected from a certain url (or urls) then show a message.

it'll be something like

[pre]

[/pre]

any ideas?