@gunnergoz I feel your pain, man. And I totally agree -- this problem cropped up only last Fall-ish. So it suggests to me there was either a system change or a sysadmin change or both. If it was sysadmin, I fear we may have all fallen prey to an idiot.
One other quick tidbit from my Tier II call that I left out of my earlier post. OK, actually two. First, the CSR firmly told us to use port 465 and SSL/TLS outbound and specifically NOT 587 STARTTLS, "because it has been my experience that port 465 works better with Outlook." No kidding? How about you update your online help to reflect that and we might not be having this call here. Second, during our support call we had to "reactivate" our primary Cox account. Why is that? "Because you have not logged in for 180 days -- it then automatically deactivates." Really? Apparently you have a lot of robots running around your networks here -- how about you write one to see if any of your services are being USED before you auto-deactivate? Yeah, how about that?
At the risk of hijacking the underlying subject of this thread, here's today's "Robot Report". My wife writes 15 of our neighbors to organize a social outing together. No 'bcc', just 15 regular ol' email addresses in the "To:" box in Outlook. Yeah, all 15 bounce with a "552 5.2.0 . . . internal error". Know what a "552 5.2.0" is? No? Google it. Some (smart, non-robot) sysadmins take the time to translate "internal error" into "automated process detected unsolicited content". Yeah, robots again. (In the jargon, "unsolicited content" is another way of saying "spam", and "automated process" is another way of saying "robot" (algorithm).) And they just blocked an email to 15 friends.
Where in the Terms of Service does it say you can't have 15 friends? This is what is called USING EMAIL you [fill-in-the-blank] morons!
This is bad. Really bad. Thankfully I DO have a choice of high-speed ISPs. Remember my cable subscription, Cox? Go ahead, keep annoying me. Last time I checked I have A LOT of choices for TV viewing over a non-Cox Internet connection. Go ahead. Just keep it up.