Email marketing is a good way to reach your target audience. The fact that you already have their email address shows that they are interested in your products and will be more likely to respond if you send them through good offers and relevant information. The main challenge you will face is putting together a campaign that will work for you.
Make sure the emails you send out are eye catching. Choose a good headline that is snappy and succinct, but attention grabbing at the same time. If you are going to include design elements, make sure they are professional and use a platform like MailChimp.
The other important factor is the content that you put into your email. Get it written professionally or at the very least, have it proofed by a copywriter or editor. Make sure your key messages are all there and are written clearly, giving people the information they need.