I have just given it a quick skim. I hope that you have put anti-spam measures in place to prevent scripts from automating submissions to your system and using it to send email. A few ideas:

* Original creator needs to register, use a confirmation email to verify them. * ReCaptcha for other writers * email confirmation before doing the final delivery to the friend.

Also make sure you have the creator write something personal for the recipient to see when they get the delivery email. I get e-cards from my relatives all the time and I always delete them.

I would also give them the option of downloading a PDF of the letters.

Good Luck!