There's no reason to be upset :) I understand it's offensive, but trying to be neutral/detached, and "professional", is IMO the best approach (also, for one's h

There's no reason to be upset :) I understand it's offensive, but trying to be neutral/detached, and "professional", is IMO the best approach (also, for one's health). You don't have resources for that (I presume), and clarify this is (IMO) the appropriate, neutral, answer; that's all. There is also another sneaky approach. You can add that you're open to commercial support, and to contact you in private for the details. I think this is also understandable, but better be careful. This will surely put things in perspective to the user. (background: I'm a maintaner myself, although I've never dealt with abusive users; I did make it very explicit though, when I didn't have resources, and users were always understanding).