diff --git a/lib/postman/client.rb b/lib/postman/client.rb
new file mode 100644
index 0000000..68ff47d
--- /dev/null
+++ b/lib/postman/client.rb
@@ -0,0 +1,61 @@
+require 'moonrope_client'
+require 'postman/message_scope'
+require 'postman/send_message'
+require 'postman/send_raw_message'
+
+module Postman
+  class Client
+
+    #
+    # Create and cache a global instance of client based on the environment variables
+    # which can be provided. In 90% of cases, Postman will be accessed through this.
+    #
+    def self.instance
+      @instance ||= Client.new(Postman.config.host, Postman.config.server_key)
+    end
+
+    #
+    # Initialize a new client with the host and API key
+    #
+    def initialize(host, server_key)
+      @host = host
+      @server_key = server_key
+    end
+
+    #
+    # Provide a scope to access messages
+    #
+    def messages
+      MessageScope.new(self)
+    end
+
+    #
+    # Send a message
+    #
+    def send_message(&block)
+      message = SendMessage.new(self)
+      block.call(message)
+      message.send!
+    end
+
+    #
+    # Send a raw message
+    #
+    def send_raw_message(&block)
+      message = SendRawMessage.new(self)
+      block.call(message)
+      message.send!
+    end
+
+    #
+    # Return the backend moonrope instance for this client
+    #
+    def moonrope
+      @moonrope ||= begin
+        headers= {'X-Server-API-Key' => @server_key}
+        MoonropeClient::Connection.new(@host, :headers => headers, :ssl => true)
+      end
+    end
+
+  end
+end
diff --git a/lib/postman/config.rb b/lib/postman/config.rb
new file mode 100644
index 0000000..5758a50
--- /dev/null
+++ b/lib/postman/config.rb
@@ -0,0 +1,15 @@
+module Postman
+  class Config
+
+    def host
+      @host || ENV['POSTMAN_HOST'] || raise(Error, "Host has not been configured. Set it using the `Postman.configure` block or use `POSTMAN_HOST` environment variable.")
+    end
+    attr_writer :host
+
+    def server_key
+      @server_key || ENV['POSTMAN_KEY'] || raise(Error, "Server key has not been configured. Set it using the `Postman.configure` block or use `POSTMAN_KEY` environment variable.")
+    end
+    attr_writer :server_key
+
+  end
+end
diff --git a/lib/postman/error.rb b/lib/postman/error.rb
new file mode 100644
index 0000000..3b6e758
--- /dev/null
+++ b/lib/postman/error.rb
@@ -0,0 +1,47 @@
+module Postman
+
+  #
+  # A generic error that all errors will inherit from
+  #
+  class Error < StandardError
+  end
+
+  #
+  # Raised when a message cannot be found by its ID
+  #
+  class MessageNotFound < Error
+    def initialize(id)
+      @id = id
+    end
+
+    def message
+      "No message found matching ID '#{@id}'"
+    end
+
+    def to_s
+      message
+    end
+  end
+
+  #
+  # Raised when a message cannot be found by its ID
+  #
+  class SendError < Error
+    def initialize(code, error_message)
+      @code = code
+      @error_message = error_message
+    end
+
+    attr_reader :code
+    attr_reader :error_message
+
+    def message
+      "[#{@code}] #{@error_message}"
+    end
+
+    def to_s
+      message
+    end
+  end
+
+end
diff --git a/lib/postman/header_set.rb b/lib/postman/header_set.rb
new file mode 100644
index 0000000..ac63a28
--- /dev/null
+++ b/lib/postman/header_set.rb
@@ -0,0 +1,21 @@
+module Postman
+  class HeaderSet
+
+    def initialize(headers)
+      @headers = headers
+    end
+
+    def [](name)
+      @headers[name.to_s.downcase]
+    end
+
+    def has_key?(key)
+      @headers.has_key?(name.to_s.downcase)
+    end
+
+    def method_missing(*args, &block)
+      @headers.send(*args, &block)
+    end
+
+  end
+end
diff --git a/lib/postman/message_scope.rb b/lib/postman/message_scope.rb
new file mode 100644
index 0000000..64196f5
--- /dev/null
+++ b/lib/postman/message_scope.rb
@@ -0,0 +1,40 @@
+require 'postman/message'
+
+module Postman
+  class MessageScope
+
+    attr_reader :client
+
+    def initialize(client)
+      @client = client
+      @includes = []
+    end
+
+    #
+    # Add includes to the scope
+    #
+    def includes(*includes)
+      @includes.push(*includes)
+      self
+    end
+
+    #
+    # Return the current includes
+    #
+    def expansions
+      if @includes.include?(:all)
+        true
+      else
+        @includes.map(&:to_s)
+      end
+    end
+
+    #
+    # Find a given message by its ID
+    #
+    def find_by_id(id)
+      Message.find_with_scope(self, id)
+    end
+
+  end
+end