Re: Not universal problem
support.microsoft.com/en-us/help/4043473/you-can-t-send-or-reply-from-outlook-com-office-365-or-exchange-2016-i
Reminds me of the EHLO farce that Exchange 5.5 did - replied with the list of facilities that Exchange supposedly supported in E5.5 - including pipelining. Which it didn't actually support.
Which is why all the emails from our SMTP hub to the (newly aquired) office in Austria were failing. Our Solaris boxes were assuming that E5.5 did pipelining (after all, it said so!) and using it to send the emails.
Which E5.5 proptly discarded.
It wouldn't suprise me if IIS on Server 2016 didn't do something non-standards compliant with HTTP/2 that broke things.
Biting the hand that feeds IT
