Hi @medma05,
If users send tokens using MetaMask directly, this won’t be via the GSN.
You will need to create a DApp that requests relayed calls via the GSN and then add funds to your recipient so that it can pay for GSN transactions.
If you haven’t already, I suggest going through the Building a GSN-powered DApp guide.
Assuming you are just getting started, depending on your development roadmap, GSNv2 is under development at https://www.opengsn.org/. You may want to look at the upcoming improvements.
You can still use GSNv1, though you may want to run your own relayer in production. See Doubling down on security for more details.