@kaardowiq As I said, after they have written to them for the first time, “mute” all contacts with Longpress. That should meet your expectations.
@SirMarc Signal has exactly all the features like WhatsApp (so to speak, “the same thing in blue” (instead of in green)), only at the same time the “feature” of not belonging to Meta, but instead being its own foundation, like Mozilla Firefox or Wikipedia, which has its own 100% open-source code published on GitHub.
