How to set Action Mailer defaults after config/initializers run?

Question

I want to store email account information in a config.yml file. I'm loading that information into a constant in a Rails config/initializers file following a common pattern I've seen online and outlined at this RailsCast. I'm trying to setup defaults for Action Mailer using config.action_mailer.smtp_settings inside the config/application.rb file, following an example on Mat Harvard's Blog. I keep getting uninitialized constant errors when starting my rails server. I'm assuming that application.rb is being called before the config/initializers. Is there another location where I can set the config.action_mailer.smtp_settings during startup, but after the config/initializers run?

Update: I may not have been clear in my initial post/question. I'm reading the config.yml file in an initializer. This config file stores email account information such as username and password. I don't want to put this information (username and password) in either the application.rb or environment.rb files. I did try moving my code to the environment.rb file, but encountered the same uninitialized constant error when starting rails.

My code to set the action mailer settings looks like this:

  config.action_mailer.smtp_settings = {
    :address              => APP_CONFIG[:email_config][:address],
    :port                 => APP_CONFIG[:email_config][:port],
    :domain               => APP_CONFIG[:email_config][:email_domain],
    :user_name            => APP_CONFIG[:email_config][:user_name],
    :password             => APP_CONFIG[:email_config][:password],
    :authentication       => :plain,
    :enable_starttls_auto => true
  }

  config.action_mailer.default_url_options = {
    :host => APP_CONFIG[:email_config][:host]
  }

I'm reading from the config.yml file to set the APP_CONFIG constant in a load_config.rb initializer. That file contains the 2 lines below:

raw_config = File.read(RAILS_ROOT + "/config/config.yml")
APP_CONFIG = YAML.load(raw_config)[RAILS_ENV]

Answer 1

You can put something like this in an initializer:

ActionMailer::Base.default_url_options = { :host => 'mysite.com' }

Answer 2

An alternative is use Figaro for environment variables:

# config/initializers/smtp_config.rb

Rails.application.configure do
  ActionMailer::Base.smtp_settings = { address: Figaro.env.smtp_address,
                                         port: (Figaro.env.smtp_port || 587),
                                         domain: Figaro.env.smtp_domain,
                                         user_name: Figaro.env.smtp_user_name,
                                         password: Figaro.env.smtp_password,
                                         authentication: Figaro.env.smtp_authentication,
                                         enable_starttls_auto: Figaro.env.smtp_enable_starttls_auto,
                                         openssl_verify_mode: Figaro.env.smtp_openssl_verify_mode,
                                         ssl: Figaro.env.smtp_ssl,
                                         tls: Figaro.env.smtp_tls }
end