What does a Thank You letter do anyways?

[heyheygirl3]

I have been wondering, What does a Thank You letter do?
I mean I have benn told that if you buy it you can choose which collectible item you get for that month.
Have I been told right?  

[Xx_VietDolly_xX]

When u open it, you can choose 1 of that montly collectible items. exSample: you buy a thank you letter for May 2006 and u can choose 1 of that month collectible.  

[Niran Silving]

3nodding what she said