Andreessen Horowitz put $25m into the B series for the company running this service, which puts a different complexion on the ROI he's hoping to get from answering a handful of emails in his free time...

tbh I wouldn't be that surprised if some of the companies willing to spend $20 to exchange emails with Ben Horowitz are actually worth his time replying to, especially if he has a PA he trusts to decide which emails are worth him having a look at.