workers/iron_mailer.worker

iron_mailer.worker

runtime "ruby"

# Naming our worker (this is an arbitrary string, we like camelcasing)
name "IronMailer"

# The actual worker file to execute
exec "iron_mailer.rb"

# Merging all of our Rails apps models
dir '../app/models'

# Merging our mailer view
dir '../app/views/mailer'

# including the email layout and putting into the /layouts directory
file "../app/views/layouts/email.html.erb", "layouts"

# including our settings file
file "../config/settings.yml"

# including the action_mailer gem
gem "actionmailer"

I think last file keyword should be:

file "../app/config/settings.yml"

Nevermind. My mistake.