6. The method of claim 5 , wherein the second number of instances is provided with more weight than the first number of instances in determining the score.
6. The method of claim 5 , wherein the second number of instances is provided with more weight than the first number of instances in determining the score. 7. The method of claim 6 , wherein an instance of the address used in a message of a more recent date is provided with more weight than an instance of the address used in a message of a less recent date.