One of the big Internet marketing breakthroughs you may hear people talking about is using direct mail.

In other words, getting the postal addresses of your email list and sending them offline offers. Many of the top Internet marketers in the world do this and swear they double, triple even quadruple their sales.

And I believe this to be true from my own tests and observations as well.

But what's even more exciting is that many of these experts are renting lists of offline people and driving them to their websites to capture their email addresses. In other words, expanding their email lists using offline lists.

However, if you decide to do this, you must be careful of who you get your lists from. There is an art to finding a good mailing list and most Internet marketers haven't really had a chance to learn about it.

Which brings me to a recent interview I did with legendary copywriter Bob Bly. Bob gave me a great tip on making the whole list renting issue painless and easy.

What he said was to never, ever rent a list from a list owner. Reason why is because you are obviously not going to be getting an unbiased answer when you inquire as to the quality of the list. A list owner can (and probably will in many cases) tell you whatever you want to hear.

And so Bob said to always go to a good list broker. A list broker being someone who finds lists for you, does all the work and then delivers you the exact list you are looking for.

The way Bob explained it to me was it costs you nothing to use a list broker since he gets paid by the list owner, not you. Plus, it is in the broker's best interest to please you and give you what you want since he wants your repeat business. If he messes around and gives you a non-responsive list, or doesn't actually go the extra mile to make sure you are happy and successful and make money from your mailing, then he knows you probably won't be back.

This may sound like simple advice. But the fact is most Internet marketers have never dealt with offline lists before and it can be a totally different animal than online lists and joint ventures.

And so, if you are going to be expanding your Internet marketing business by going to offline lists and trying to drive them to your online list, make sure you consider the advice Bob gave in the interview.

It could save you a lot of time, money and frustration.