Force Forum into iFrame using PHP

[bezworks]

I have my board in an iframe on our site. When someone receives an email notification about a post or private message, it gives them a URL to the forum OUTSIDE of the iframe.

What modifications can be made so that either:

1) The page recognizes the URL, modifies it, and loads it into an iframe

or

2) Alter the email system so that it a URL that targets the iframe.

Thanks!