An ex has written a letter to my husband of three months. What should I do?

My husband of three months has received a letter from an ex that he dated four years ago. The letter was mailed unsealed so that's how I came across the contents. I am debating whether to respond to the female and let her know that we are married and to stop writing him. (She got our address off the internet) Or I'm thinking of giving the letter to him and see what he does to handle the situation. Or just ignore the letter all together. My husband is in the military and is gone a lot of the time and I don't know if I even want to bring this letter up. Im not insecure because he married me. Im just undecided on the action I should take because I want to be a better person for 2009. 2008 I would have immediately called and let her know how I felt about her confessing her undying love and being miserable without him. I would love to hear some advice from married people.