If you're running a promotion which you think every visitor to your website should be shown, do think about this approach.
A "squeeze page" is a web page where you can only do one thing, normally submit your email address to a mailing list or for more information. They got the name because if done right, with a great offer, they "squeeze" every last email address out of the audience. They've not been in fashion in recent years, because the trend online has been to allow website visitors to make up their own minds about what to do, not to force them down a particular path. But they still work, and have come back into the spotlight recently by featuring on one of the highest profile websites in the world, that of the US Government (whitehouse.gov). If the squeeze page isn't running at the moment, you can see some examples of what they've been up to here.
The initiative has avoided the normal criticisms by offering a degree of courtesy which makes everything all right. Yes, the first thing you see is the "offer". But if you don't want to take it up, the next place you'd look would be at the perfectly reasonable button which says: "No thanks. Go to the website." No catch, nothing hidden. Seriously, who could complain about that?
If you're running a promotion which you think every visitor to your website should be shown, do think about this approach. For example, if you have a great email offering, or if you're known for your catalogue, you could pop up a full-screen offer over the home page, especially for first-time visitors. Most web designers could do it for you.