I have been googling for about 90 minutes now and still don\'t have an answer to this. Where do I set default_url_options? I\'ve already set it for conf
I solved the issue by configuring environment.rb as
YourApp::Application.default_url_options = YourApp::Application.config.action_mailer.default_url_options
You need to set default_url_options for action mailer against each environment like development, testing, staging and production etc.
Reference: Missing host to link to! Please provide :host parameter or set default_url_options[:host]