Gee... well behind the times here ....
JUST noticed the email notifications from followed posts/threads have a dynamic from email address. Up until somewhere between Aug and Oct 2018 emails came from firstname.lastname@example.org, but since then emails seem to come from forum[postnumber]@geekzone.co.nz.
Its a fantastic idea as it allowed email threading to work better.
Had a very quick look over this forum group, but could not see anything suggesting the change so just had to fill everyone in ;-D