How to get old customers on email list?

Hey @CC_email 

Thank you so much for asking the Klaviyo Community for help! 

If you are looking to clean up the consent info. One thing you could also try to make a segment of those profiles and make a signup form that targets those people that haven't given explicit consent and see if they opt-in through a klaviyo form and sync that appropriate consent. This way you are grabbing the customers who are active on your site again while protecting your sending reputation from over sending to customers that may fall into their spam folder. 

Hope this helps!