mail_receiver_example.rb

#Instead of the following
Mail::Configuration.instance.retriever_method :pop3, pop3_options_hash

Mail.all.each do |mail|
...
end

#I would like to write one of the following

#1. The following line will instantiate a receiver using the global config
email_receiver = Mail::Receiver.new

#2. However, this one will only initialize the instance with specific options
email_receiver = Mail::Receiver.new :pop3, pop3_options_hash

#3. One can also take a hybrid approach, that is starting with the defaults and making customization as follows
email_receiver = Mail::Receiver.new
email_receiver.user_name = 'my_custom_inbox@example.org'
email_receiver.enable_ssl = true