In the openSteam backend, we wanted to give the admins the possibility to manually activate or deactivate mailer, like order-confirmation or user-signup mails.

We built a model, called SystemMailer, which holds the mailer classname, the mailer method and a boolean.

Migration File:

   1  class CreateSystemMailer < ActiveRecord::Migration
   2    def self.up
   3      create_table :system_mailers do |t|
   4        t.string :mailer_method
   5        t.string :mailer_class
   6        t.boolean :active
   7  
   8        t.timestamps
   9      end
  10    end
  11  
  12    def self.down
  13      drop_table :system_mailers
  14    end
  15  end

Model:

   1  class SystemMailer < ActiveRecord::Base
   2    def active? ; self.active ; end#
   3    named_scope :active, { :conditions => { :active => true } }
   4  end

Then we built an alias method chain for the ActionMailer::Base#deliver! method, to check whether the current mail-method of the current mailer is active:

   1  class ActionMailer::Base
   2  
   3    def deliver_with_active_mailer_check!(mail)
   4      active_mailer = SystemMailer.find( :all,
   5        :conditions => { 
   6          :mailer_class => self.class.to_s,
   7          :mailer_method => @template,
   8          :active => true } )
   9  
  10      return nil if active_mailer.empty?
  11  
  12      deliver_without_active_mailer_check!( mail )
  13    end
  14  
  15    alias_method_chain :deliver!, :active_mailer_check
  16  
  17  end

In this alias-method, we try to fetch an active SystemMailer entry (with the current class and method name). If the results are empty (no active SystemMailer found), we return nil, otherwise we call the original deliver! method. Pretty simple.