When you consider that building a successful business can depend on both quality and quantity, choosing the best course of action would largely depend on the company's goals. Both have their merits and their challenges.
Email marketers answer the question more definitively. Quality definitely TRUMPS quantity.
When a client starts their email marketing program, they often want to take the fastest route and use someone else's mailing list to get them jump started. Well, this is a definite no-no. For one, the *"Cann-Spam Act" which all email marketers should be aware off, expressly forbids this practice. To get the best results from your email campaigns, you want to make sure that you are communicating in a useful way with your clients and potential customers interested in what you have to offer. Quantity doesn't work here as your message would go to the masses but would they be interested in what you have to say or offer?
Be patient as it often takes time to build up your following. Build your list slowly, effectively and efficiently. Use your website, social media channels and word of mouth efforts to let people know how to stay in contact with you and your business. Using these methods will go a long way in building and keeping a quality email list.
*The CAN-SPAM Act (Controlling the Assault of Non-Solicited Pornography And Marketing Act of 2003) is a law passed by Congress and signed by President Bush in 2003, requiring national standards for sending commercial emails.