belongs_to :sender, :class_name => "User", :foreign_key => :from_user_id
belongs_to :recipient, :class_name => "User", :foreign_key => :to_user_id
validates :title, :presence => true, :utf8 => true, :length => 1..255
validates :body, :sent_on, :sender, :recipient, :presence => true
belongs_to :sender, :class_name => "User", :foreign_key => :from_user_id
belongs_to :recipient, :class_name => "User", :foreign_key => :to_user_id
validates :title, :presence => true, :utf8 => true, :length => 1..255
validates :body, :sent_on, :sender, :recipient, :presence => true