README.md in spree_sendwithus-2.0.11.6 vs README.md in spree_sendwithus-2.0.11.7

@@ -26,9 +26,16 @@
   config.api_key = ENV["SEND_WITH_US_API_KEY"]
   config.debug = true
 end
 ```
 
+If you want to globally configure the email service provider SendWithUs will use, say for sending staging emails to something like [mailtrap.io](https://mailtrap.io/), then simply add the following to an initializer:
+```ruby
+Spree::SendWithUs::Base.configure do |config|
+  config.esp_account = ENV['SEND_WITH_US_ESP_ACCOUNT']
+end
+```
+
 Now you can configure any of your mailers to use SendWithUs by making them a subclass of `Spree::SendWithUsMailer::Base`. For example:
 ```ruby
 # app/mailers/spree/quality_control_mailer.rb
 
 class Spree::QualityControlMailer < Spree::SendWithUsMailer::Base