Depending on her email domain, they certainly could automatically be vectoring group posts to the spam/junk file.? If she doesn't actively check that folder for valid messages that got put in there and mark it "not junk/not spam" - then the filter will continue to mark it thus, and as said below, once the automated system takes over, the user likely will never see it.? She can get mad all she wants, but in the end, it is she, not the system, that has the responsibility for making sure the posts from groups.io are marked as "safe" (or "whitelisted" or whatever terminology her anti-spam/anti-malware filter uses).
Bill HIckey
Boulder, CO
Bill Hickey - WA3H