How To: Set :host and :port for all devise mailer urls

If you find yourself needing to set a :host and :port for your mailer url's (e.g. when sending a reset password link) follow the instructions for overriding the devise mailer here and then follow these steps:

Create a file in app/concerns called default_url_options.rb. Depending on your version of Rails you might need to add a setting to your environment that loads files from this folder automatically.

In this file put something like the following:

`module DefaultUrlOptions

Including this file sets the default url options. This is useful for mailers or background jobs

def default_url_options { :host => host, :port => port } end

private

def host # Your logic for figuring out what the hostname should be end

def port # Your logic for figuring out what the port should be end

end`

Next, just include this module in your devise mailer:

`class UserMailer < Devise::Mailer
include DefaultUrlOptions

end`

It's worthwhile noting that you'll need to be able to figure out the host and port in the above example without having access to any request object as mailers and background jobs run outside the context of the request.