Hello Hornblower and first of all thank you very much for the great support!
My Outlook computers are configured so that emails on my main computer are deleted from the POP server after they have been downloaded. The external computers are configured so that emails remain on the POP server. Unless I delete them because of spam, advertising, etc.
I've already tried that with a different profile and a different .pst file. The result was the same.


Here's what I'm going to do now. I still have the original SSD with the original Dell Windows 10 and no MS Office. I'll install this SSD in the next few days and install MS Office 2021. I'll configure Outlook with a dummy email and then see what the send/receive window looks like, i.e., whether the OK/Cancel buttons are there.


I keep you updated!