I have a question for you guys I have a huge amount of emails about few millions. Emails are 99% active and high quality but users did not subscribe to any list. I am able to check their interests but only manually so I would need whole day to check about 300 mails. Can I make any profit of that list and what offer can I send them? What is better: to check their interests and send 1k-2k emails a week with appropriate offer or to spamm they massive with some not personalized offer?