From December until February 13th, 2012 [confirmation on the february date still pending] you can send letters to Kaitlyn with this address:

Sister Kaitlyn Clarissa Waters
MTC Mailbox # 319
AZ-TUC 0213
2005 N 900 E
Provo, UT 84604-1793

Also, is a FREE and quick option the entire time I'm in the mtc. And once I'm in Arizona, each letter only costs the amount of a stamp.

For the remainder of her mission, send letters or packages to the mission office:

Sister Kaitlyn Clarissa Waters
Arizona Tucson Mission
939 W Chapala Dr
Tucson, AZ 85704-4516
United States

* Kaitlyn's sister Kelsey will stay up to date on any address changes for specific areas, but these addresses will always remain constant