>Thank you (and others who contributed to this thread) very much for your helpful input. But here is a twist. I have not done anything related to this problem yesterday. I just turned on my PC (it is a holiday in the USA today so I don't have to be in the office early); then started Outlook and all emails - including GMAIL - works. Another strange thing is that today, when I loaded Outlook, I didn't get the message "the server you are connected is using a security certificate that cannot be verified. Do you want to continue using this server" (the image 1 I attached to my earlier message to you). Which leads me to believe that the problem does have something to do with the security certificate. For now I will document all that I experienced with this problem because you never know if/when it happens again.

Perhaps you weren't the only one with the problem, so some noise was raised elsewhere and thus became the squeaky wheel which gets oiled on a weekend? IOW, something was updated somewhere beyond your network cable, and the pieces now talk to each other much better than before?