+
+ validates_presence_of :title, :body, :sent_on, :sender, :recipient
+ validates_length_of :title, :within => 1..255
+ validates_inclusion_of :message_read, :in => [ true, false ]
+ validates_as_utf8 :title
+
+ attr_accessible :title, :body
+
+ def digest
+ md5 = Digest::MD5.new
+ md5 << from_user_id.to_s
+ md5 << to_user_id.to_s
+ md5 << sent_on.xmlschema
+ md5 << title
+ md5 << body
+ md5.hexdigest
+ end