MyBB Community Forums

I ticked:

Can send threads to friends and email users?

and they can sent
Maximum Emails Per Day: 1

So what is wrong here?

My board is www.interviewedyou.com/forums

Regards

You can never do this i don't think.
As you need permissions to send e-mails from a guest.

If anyone who isn't logged in can send emails, that's basically an invitation for spammers.