In T7247#102317, @sevens wrote:

...

Test sending mail

Tested:

• ...
• Sent a mail to my personal address (on personal domain)

Results:

• ...
• The test mail sent to my personal address didn't arrive either, but I didn't expect it to

...

Some quick further testing.

So I finally had some time to look into this some more. First, thanks to all others for their notes and further progress, this helped me today as well. I only had some of the issues others had, possibly as they have been fixed in the packages/upstream in the meantime, and hit some issues not yet mentioned here as well. What follows is an extensive log of and some notes on the relevant parts of my updates, changes and fixes since my last comment. Hoping this helps others further along as well.

In T7247#99901, @ghane wrote:

Thanks for the debugging

Ok, here we go; this is a long one as I encountered quite a few issues, but hopefully much of it is useful...