Mailpoet Sending paused

When people try to subscribe to our mailing list they get an error message – Something went wrong with your subscription. Please contact the website owner. – they never receive a confirmation email although they appear to be added to the list. I noticed on the WordPress Mailpoet Help section that sending has been paused. I cannot see any reason for this. Since we installed we have done 1 mailing to 200 or so people on 2 lists and response is marked as Excellent with 54% and 15%. It is possible that Mailpoet has bee paused because of my troubleshooting this error for 2 days now which included multiple send attempts. Does anyone know what I should do to lift this pause?

The page I need help with: [log in to see the link]