In the long term, your website will be the number one generator of new subscribers, due mainly to the fact that it can be promoted in so many ways. Additionally, a website is important because it provides a permanent, stable home for your ezine.
Email is ephemeral by nature, and is often forgotten once received.
A website, on the other hand, will work for you 24 hours a day to generate new subscribers. The most important element of a website to promote your ezine is the subscription form. Put it on the front page of your site, in the first screen view, so visitors don't have to scroll to find it. If your site has multiple pages, consider putting a subscription form on every page. Once you've planned the content of your site, you'll have to find a place to put it.