Letter about mineral ownership - but do we own anything

We received a letter about wanting to discuss our mineral rights addressed to my mother, who passed a few years ago. I assisted her in selling all the mineral rights she had. I have searched and I cannot find any more. Is this phishing? Could they be mistaken?

The offer may have been generated based on an old list of mineral owners, particularly if it is just general and does not list specific property.

Thank you, that’s what I’m suspecting. I reached out to them and they are going to get back to me. But I did my own look and I see nothing attached to my mother’s name that she didn’t sell prior to her passing.

She didn’t even know about her stuff as it was my grandfathers and he never told anyone .