It's all spam in the end, so you run whatever risks you are comfortable running. Simply put - you cannot send unsolicited email to people trying to sell them things legally. Does that stop people from doing it? Of course not, but it requires a level of diligence and an understanding that if caught you may incur financial penalties that effectively render you penniless. This is true of all email addresses that were not acquired by you unless the person who joined a list explicitly stated it IS OK for their address to be shared with partners of the location the email address was acquired. Certainly if you acquired the addresses by scraping CL - you are asking the question "How can I legally spam these leads?" There is NO answer for that. However, you can take whatever risks you are comfortable taking in your businesses.