Is it legal to send mass email to all my contacts that I got over time on craigslist.
 

If I have got a few thousand emails from people that I have dealt with on craigslist, amazon, ebay and other sources and I wanted to make a e-mailing list to send them opt in links for biz op is that legal since they didnt opt in yet. They have all emailed me at some point in time so I didn't use a crawler or anything....................... Is this legal I might want to sell the lists as well

Some countries have banned email marketing, if you will send them promotional email then they can take action against you.