You need an email marketing service that manages emails for you.  Examples of these are companies like MailChimp, Aweber, Constant Contact, Mad Mimi, and Vertical Response.

This is a non-negotiable expense for your business that helps you to organize, schedule, and deliver your email campaigns.  They also keep your business compliant with anti SPAM laws.

I recommend using MailChimp, it is free to sign up and use until your list is larger than 2000 subscribers and the free account includes the features you need to get your business going.