Thought I should post this as it came to me on a newsletter this Month, Jan 2024
Beginning next month (Feb), major email providers like Gmail, Yahoo, Hotmail, etc. will be requiring bulk email senders (all the newsletters you love) to send from an authenticated custom domain email. In brief, there will be even more filtering to your spam/promo/trash filters for folks who use these free email services.
It seems e-mail providers are trying to force free users to upgrade to their packages, by spamming mail and also reducing size of inbox viewing, usual sh....t x
Another point to add is that the person who sends out the 'newsletters' has now taken that word out of her e-mail address to assist delivery...