Earlier quoted context omitted.
What was the problem?
It was a SharePoint issue with the emails it sends out and it ended up being a permission issue (well, not even sure you would call it that - but the fix was resetting the system account's password). There had been no changes in accounts or anything else besides the creation of new sites and to make it even harder no error messages or useful logging. I've seen issues like this more times than I can count over the yea…
OTOH, SharePoint extraction tools seems to me a very profitable model for the coming years.