Matt Wagner has made a wonderful program which helps produce the letters to notify other states about individuals who have now registered in your town.
Once you have downloaded the program, you will need to unzip it, and make note of the location. The file you will need to execute is called: "Out of State Reporting Tool.exe"
In addition to the program, you will need to download a Voter.txt file and an AddressHistory.txt file from CVRS. Once these are loaded, the letter generation is easy.
Don't be daunted if the above sounds confusing. It's easier than it sounds, and a huge time-saver.
Also, click to open Every State's Election Office address list in a new window if you prefer to send postcards or otherwise maintain a manual process.