What's their basis for sending the emails then? If not one of legal standing in copyright/contract law?
Edit: My point is this is just another one of many annoying people you have to deal with who will email you alleging all sorts of legal violations, who don't themselves understand anything about the claims they are making.
Sure, I understand that there's a difference. That's why I sought clarification.
My understanding of the concept of "basis" does not fit the context of sending an email, and "reason" is the closest I can find that fits.
Basis being concerned with rules or authority. The assumption being when asking "what is the basis for X?" that there was a bar that needed to be met beyond the doers motivations. That there needed to be more than they wanted to. Which of course, does not apply to sending an email. I could email you right now asking you what your favourite type of fish is or seeing if you want to play a game of chess, no basis needed. I'd just need a reason to.
Poorly explained maybe but it covers not just that there is no basis but that no basis is needed and draws attention to the odd request for a basis where none is needed.
Just "there is no basis" as a response would be like saying "yes" or "no" to "have you stopped beating your wife?"
Edit: My point is this is just another one of many annoying people you have to deal with who will email you alleging all sorts of legal violations, who don't themselves understand anything about the claims they are making.