I agree with Magda - email marketing is a perfect way to connect with your previous and potential customers. It can help you boost sales, as selling to previous clients is 8 x cheaper than finding new clients. It also makes have regular sales, not depending on your Google rank - your sales won't drop if your sales with suddenly go down in Google pages. And it can happen - I've seen shops with the sales wiped out overnight, as their website dropped from page 1 to page 3 on Google overnight [it happens].
If you are not sending regular newsletters you are taking big risks:
Missed opportunity to sell – being visible and present in your customers’ minds mean more sales. Don’t be shy.
Irregular contact affects trust – you see, customers want to know you’re here to stay and have solid grounds. They want to trust you with their money and personal data – and to know you deliver. By not sticking to your mailing schedule you give signals you cannot be relied on.
Subscribers will forget about you – after all, they subscribed for a reason, if you disappear from their point of view, they will not visit your store next time they’re shopping online.
Hope it helps!