We do honor blackhole routing via the DE-CIX Frankfurt Blackhole Routeserver.
If you do announce attacked /32 hosts to the dedicated Blackhole Routeserver in Frankfurt, we will accept the announcement and send your traffic to the traffic burning ip address or burn it internally.
For more information on this feature see here:
(Also find a FAQ and a whitepaper there too)
Another source of information is the DE-CIX Academy homepage: