Your best shot is to hit up forums that are related to your niche. I would do a google search for recipe forum, cooking forum, etc and look for ones that have a decent userbase but not too much otherwise you wont get a good advertising deal with your banner display ads
You can contact bloggers in your niche that have a well established following and are willing to let you tap into their user base in the first place.Have your hot offer ready in exchange.
Do you have everything setup on your site? Autoresponder? One tip. No matter which forum you are on you should always use your signature for your links. Even though this is an IM forum you still have potential leads. Everyone loves a banoffee pie! I can also offer you some free traffic. check out my earlier digital point post
There are several sites those provide email list on basis of your need. But you may have to spend some for this visiting americaint.com can be helpful for you.
What are planning to do with your email list? Nowadays you cannot send just to everyone without their permission.
Sending emails without permission is illegal and I believe email marketing is an permission based marketing. Major ESP's would also like to know how you collected all these email ID's and won't allow you to use their software if you have not collected email adressers with user's permission.
Don't focus on finding email lists. Generate your own. Scan related forums, blogs, etc. to make connections and acquire contacts. Also, if you are emailing people that have never been on your site it will likely be classified as spam. To run effective email campaigns, you must collect the addresses yourself first.
grab a copy of my free guide templates. It takes you through the process of setting everything up by the hand. Weekly tips for getting free traffic too.
Place a opt in form on the website and naturally build a list.....add a section with special content that requires a subscription