Also received the same awesome QSL here for the November 4, 2017 test! Thank you very much shortwaveradio.de!
Mentioned in the email was the following:
Our transmission times are as follows (Monday to Saturday):
3975 kHz: 1200 - 1400, 16:00 - 1800 and 2000 - 2200 UTC
6160 kHz: 1000 - 1200, 14:00 - 1600 and (2000 - 2200 UTC - off at the present time, due to conditions)
There might be the chance we will switch on our 6160 outlet between 2000 and 2200 on Saturdays. So, overseas DXers might have a chance ;-) However our main target area are the UK, Eire, Belgium and the Netherlands.