Back in 1997, I designed and develop a package software that enables people to send email to multiple recipients and call it "NewsMAIL". After 20 years later, we still provide NewsMAIL as a Internet Service under NewsMAil.com
Email marketing is one of the most effective marketing tools available to businesses but most people are not using this technology right. First of all, you should never send email to a mailing list you purchased. It is clearly a SPAM.
NewsMAIL is an effective communication tool for you to communicate with your existing customers and contacts. And there should be two call to action on your email.
(1) Promote Upgrades / Optional Services / New Services to existing customers. Consider it as a communication tool rather than sales tool.
(2) Ask you customer to share the contents to their contacts. If you are providing valued services, your contacts should be able to help you do that. That will benefit your contacts.
If you use email as a cold calling tool, you are not doing any good to your business. You will be just blacklisted. If you need to know more about NewsMAIL marketing, please contact me.