Licenesed US sportsbooks only, no offshore tickets.
Both Nevada and Illinois are not allowed either.
PropSwap can reject any ticket offered to them for the site.
For the buyer, you will get the hard ticket and can go to the origianl sportsbooks or mail in to collect.
You can be a buyer from non legal states, like California.
They do not tell you where the ticket is from, it's not disclosed.
So much is done over the mail and if there was something "lost" then PropSwap can actually contact the originating book and put the bet on hold.