Hi Dolores,
You are asking such a great question, and it's one that is asked quite frequently! No one really knows how and why pin codes are mailed randomly to Guests. It's one of those pixie dusted emails that Disney Parks loves to surprise their Guests with from time to time. I've frequented Walt Disney World quite a bit in my 30-some odd years, and I just received my very first Walt Disney World pin code email a few days ago. See? Very random.
Some suggestions I've heard are to sign up for any official Disney Parks giveaways that are offered, take a few minutes to plan your dream Walt Disney World vacation through the website and to sign up for the free
Disney Parks Vacation Planning DVD. Now, there is no guarantee that these steps will cause a pin code email to arrive in your inbox, but it doesn't hurt to try!
I hope this helps you, Dolores. If you have any other questions, please ask us at any time.
Have a fantastical Disney day!