We have talked a lot in this blog over the months about where to source email marketing lists, and have always suggested that the BEST source of lists is those people who already know you, and this is still our advice re best practice. But when is it legitimate to use bought/rented lists? Most people would say the answer to this is NEVER, and although I would agree that this should be the default position, there are exceptions in the B2B markets. The grid below gives a broad outline of the situation: 
In summary our recommendations are as follows:
- ALWAYS use warm (Lists of people you know) as the first option
- NEVER EVER use cold (bought in/rented lists) if you are targeting consumers – This is not allowed under EU/UK law
- If you are considering using a cold (bought in/rented) business to business list, do so with EXTREME caution, as using these lists “straight out of the box” will lead to no end of problems, even if they are from highly reputable sources.
If you are considering this option, I would suggest you read these posts on the subject first:
