mta2.rapidmail.de has no TXT records.
Question and response
Question
dig mta2.rapidmail.de. TXT
Answer
The response has no answer records.
Authority
rapidmail.de. 180 SOA ns10.digicertdns.com. dns.digicertdns.com. 2009011419 43200 3600 1209600 180
Additional
. 0 OPT ; payload 1280, xrcode 0, version 0, flags 0