A Cyber "Wrong Number"

You get an online greeting card from a stranger. You realize it was sent to you by mistake and from the included message, you understand you could reply as the intended recipient and get away with it. You like this person sending the greeting. You like the way they write. You would like to get to know them.

But, you are a decent person so at what point would your conscience bother you and/or compel you to do something? What becomes of the friendship and/or romance with this online sender? What complications ensue?

Perhaps this is not a romantic comedy. What if the sender is a psycho-killer? A terrorist? Involved in a conspiracy? And now they think you are one of the members of the criminal gang.

How have you grown or changed by the end of the story? How is your life different?

NOTE: "You" could be you, writing in first person, or it could refer to a character you create.