massive mailer questions

hello, i'm thinking in joining a venture with a friends of my (a coder guy) we are thinking in make a massive mailer app.

we are thinking in let the user use the app in two modes:

1. free (but mining monero at 20% of the computer power and sending a message to the user that the app is mining at 20% of the pc power in free mode)
2. pay mode, a month fee for "x" amount of mails but with the mining deactivate.

what do you think about this monetization scheme ?

sorry if I posted this in the wrong forum and thanks in advance for all your help.

You can have the free users fill in CPA every time they use it free.. It is annoying so they will eventually get the paid version

I'm not sure I understand correctly, are you talking about a autoresponder?