I have a client that wrote an report on how an e-mail address is worth $2-5 dollars for store. I argue that this is not true, there are many variables. For example there are databases online with 4 million consumer e-mails for $0.18 cents an email.
I need an expert in the field to write a report proving this, that email address are valuable if is not spam list, if they actually opt in, and if they actually bought an item in a store. Spam lists are not valuable and even then an e-mail is not worth 2-5 dollars but cents like many online databases selling bulk email lists shows.