How much are email addresses worth?

Hi guys, I was wondering how much email addresses are worth nowadays. I run a adult website with the option to create an account with email address. About 7500 have shared their email address.
I know this answer has been on BHW before, but they are quite dated.

Depends on the niche/subniche and the guy you sell it to. There is no definitive answer, but IMO I would not sell my private list.

A major chunk of adult site visitors use a throwaway email. That makes it hard to determine the value of such emails.