ruby on rails - Prelaunchr mailer not working -

i running harry's prelaunchr (https://github.com/harrystech/prelaunchr) on heroku , welcome email supposed send out when new user signs on site not sending out. rails app using delayed::job , when run

heroku rake jobs:work 

i following output:

 rendered user_mailer/signup_email.html.erb (1.2ms) [worker(host:46d2c895-5e66-464b-8594-510461de915c pid:3)] class#signup_email failed actionview::template::error: undefined method `encoding' {:host=>"windreturns.com"}:hash - 9 failed attempts 

^note: host=>"windreturns.com" domain, not site located (it's genericname.herokuapp.com domain)

any idea why jobs failing? how emails send?