What do you mean with "email id"? You can use Magento's newsletter engine to send out an email with coupon.
Or you can use a 3rd-party extension if you need something special. For instance, the Abandoned Carts extension. It allows to send automatic emails when:
1) Customer has products in his cart for X days but has not yet purchased them. So you can send an email with coupon.
2) Customer has not yet purchased products in his wishlist for X days. Send a coupon to convert wishlist into a purchase.
3) Customer not logged for X days. Improve the social activity.
Hope it will be of help.
Please take a look at our Follow Up Email extension enabling you to send coupons, or email chains with increasing coupon values, and track your coupon statistics from the backed.
Follow Up Email - https://goo.gl/KHu4F9
You can send followup emails and share what ever information you need with your customers by using Magento followup emails extensions
You can automate the whole system, send followup emails automatically, and lot more features.
Please check demo
You can do this with an extension we're building. Additionally, the distribution module allows you to send coupons with:
If you want to try it out, sign up for a closed beta program with the link above.