Madeleine Wells is Amélie's lonely landlady. Her husband used to write her stacks and stacks of love letters before they got married, even calling her his "sweet little weasel" in them. Yeah, it's supposed to be adorable.
Well, after they got married, this guy cheated on her and flew to Panama with his secretary. Later, he died in a car crash. Madeleine has cried ever since. When her dog died, she even had it stuffed so that it could sit staring at a portrait of her dead adulterous husband. "Wells as in water," she says, describing her name. "Talk about being born to cry."
Amélie wants to bring some peace to her landlady (or maybe she's just sick of hearing about it), so when she hears about a recovered mail plane that went missing around the time Madeleine's husband died, Amélie "borrows" Madeleine's letters, photocopies them, and uses the copies to create a fake letter, which she pretends was recovered from the plane. In the fake letter, Madeleine's husband confesses that he always loved her and hopes she will join him in South America.
Even though the letter is a complete forgery, it brings Madeleine peace, so that makes it okay, right? Well, according to Amélie, yes.