I would write the letter as an answer to my friend's having asked me what it was about Annabel Lee that was so enchanting. I would then give the letter a fairy-tale like quality of how she was only created for me to love and be love by her, how we were at one and whole in our own little world. Even in death, nothing can separate us from each other because our souls are tied together forever. I would live and die by her side for all eternity.
Sure. If I were writing such a letter, I would try to make it realistic, but fun. For example, I would include references to shared experiences in the letter that have nothing to do with the poem. (Poe was a great gambler; perhaps he could refer to shared card games?) I'd then talk about the poem. I'd probably make this letter part of an ongoing exchange, perhaps even say that Poe had talked about the poem with the friend earlier. I'd then use the information found in the analysis section of the enotes study guide to explain the poem to the friend: