Potential guest asked for pre-approval to help with getting a US visa (traveling from Italy)?

[Oscar1208]

I have a potential guest inquire about my listing. I believe they are traveling from Italy to the US for a few months. They asked if I could pre-approve the reservation to help them get their visa. They will not book yet until next week once they’ve entered the country. I always get suspicious when people message me asking for this type of help because I have traveled abroad many times and always make sure I have secured my hospital before I even hope on a plane! I understand you are required to provide where you will be staying so that part I get. Does anyone know anything that would help me address this? I also read that a pre-approval will not be sufficient when applying for a visa. Thanks!