you can thin it out a bit by asking anyone who’s interested to email you and you’ll send the MS by reply. That at least filters out those who (for all sorts of good reasons) weren’t really interested but were just being polite.

Why do you have to let them? Are they all writers/editors/professional reviewers? Is your book a memoir and you want to prevent them suing you?

I do not give my books to friends and family, only book friends

Why do you feel you need to? Mine only get to read my books when they’re out. Friends and family feedback is dangerous - they’ll either feel obliged to say it’s wonderful or disappointed you when they don’t read it.

Feedback from family and friends is not helpful and can be damaging. You need specific, constructive feedback. There is no need to pay for this. You form a critique group and build relationships with other writers as you learn the craft of writing, editing and providing feedback.

If you just want some first reactions, be clear about that. It's fine to say "At this stage, I don't want notes or criticism, just praise and optimism." If you want constructive feedback: set up a google form or something similar with open but fairly specific questions for them to answer. Be clear about what you do and don't want feedback on, and remind yourself that they might not be your target audience. It's also absolutely fine to separate friends and family between the two ;-)