Bigger is not necessarily better when we study the effectiveness of e-mail lists. For best results, e-mail lists must be kept up to date. We have to filter out the e-mail addresses that are too old and non-responsive. It is better to have a smaller list full of interested people than a large list with prospects no longer interested in what we offer. The key is to prune the list.

For starters, break the list based on age. By age I mean, how long have we had the e-mail in our list. For example, we could have a list of subscribers that are newer than six months old and all others. We could e-mail our newer list more frequently than the older list. If we have a list of e-mail addresses that have not responded to any communication in the past six months, we could move them into another list. Then, delete e-mails that don't respond to our e-mail for another three months. In this manner we slowly weed out inactive e-mail addresses.

Think quality not quantity because e-mail marketing success is all about quality.