Thanks for your further info, Woody.
Oddly, I also had a couple of AP group emails that lost their way for 4 days last week, finally returned to me as “undeliverable”.
When the Yahoo service was flakey about a month ago, or so, we here, all got an apology from Rogers our ISP, about Yahoo’s problems that weekend. They may still be tweaking the new Yahoo system.
Since others have reported no problems today, maybe Yahoo is running “regional” tests, so some are fine, and others not so much, recently. They may be briefly cutting off certain ISP’s for example.