In the letter, you can reword to say, "If you are unsure of your status, please go to
www.msb.gov and view the regulations."
What I ask for depends on the size of the relationship, but at the very least I would get a copy of the MSB registration, the Check Casher license and the occupational license from the city or county.
I also get a copy of their AML policy.
If they cash checks payable to a corporate I review the files that they maintain on those corporations.
For risk purposes and expected activity, I request three months bank statements so I can see the volume of returned items, average balances, cash orders etc.
Hope this helps you.