Suicide - contemplation

Imagine receiving a question late at night from someone that says something like, "My life is meaningless and there is no point in living. If you don't convince me otherwise, I am going to commit suicide in the next hour." What would you do? What I did the first time this happened: I wrote the best possible response I could come up with in 10 minutes and sent it to her. Thankfully, I heard back, and she stated that she had decided not to commit suicide, but, unfortunately, I never heard back from her again after that.