It goes without saying that building your list is of vital importance. It’s been hammered home time and time again on this very blog. What hasn’t been discussed, and may surprise you to learn, is the rising popularity of email lists that can be bought outright or just rented on a “per use” basis. This is likely a subject with vocal critics on both sides of the fence, but it’s hard to dismiss the fact that “email lists” was the favorite search phrase last month from those seeking information about email newsletters.

Lots of people are very attracted to the idea of acquiring a ready-made list of email addresses they can send promotional emails to. Instead of spending months to slowly build up a list of email addresses you can piggy-back (for a price) on someone else’s efforts? While the idea may seem appealing, here are a few details for anyone who considers taking this course of action.

List rental is an accepted and well-recognized practice in email marketing. Owners of address lists will send an email to their list on your behalf and you pay a fee for this service. The key factor is that you never get to see the email addresses on that list. The list owner handles the sending, not you. Essentially, you need to understand that — unlike with direct mail — the actual address list never falls into your hands. Therefore, you pay a rental fee every time an email gets sent to the list.

The alternative is to purchase a physical copy of a list of email addresses. After you pay the owner’s price, there are no further fees to pay. You can send your promotional message as often as you like to the list.

However, there is a downside purchasing a bulk list like this. Once the owner of the list has decided to sell it to everyone willing to meet his price, nobody is controlling how many emails or even what type of emails people send the list. The value of that list is only preserved if those who buy it don’t abuse it. Send too much commercial email and people soon stop responding. They may even report you as a spammer.

So when you see offers like 1 million addresses for $100, 99 times out of 100 you’re getting a spam list. That’s a list of addresses of people who have not agreed to receive messages like yours, or who are on a list that’s been blasted to uselessness by other mailers.

Another option is to pay for email addresses through co-registrations, where other websites invite people to sign up for your own list and charge you a fee for the service.

There really is no substitute for building your own list of email addresses from people who have requested to get commercial messages from you. Homegrown, house lists are by definition matched to your needs, since people are proactively choosing to get your messages because they want to hear from you. And you pay no rental fee when you use that list.