Retargeting with zero opt in lists?

[K]

So lots of people get hold of big lists and are not sure what to do with them because they are not there own opt ins.

One idea I was reading about was to retarget the list using FB or Adroll maybe, as I'm pretty sure on both you can target email addresses.

If you know the source this could be a "legal" way of using the list? correct me if i'm wrong?

 

[abuhanifa]

retargetting works wonder. If you know the source , you can double or triple your ROI .

 

[Effect]

Great tip and lesson, thank you