Subscribe by Email not Working

When I try to add a subscriber it doesn't work (no email confirmation is sent, and if the auto opt in selection is checked, their name isn't added). I've tried with the widget checkmarked not to send an email, and with the follow link at the bottom: with the follow link on the bottom I get to a blank page with only the words "bool(false)"

I've tried to send a test email and it works. And that test email also sends out a removed confirmation to me, if you click the link to unsubscribe in the test email, so I know that email from the site is working.

Wordpress Multisite 3.6