mail55a.sapsf.eu has no CNAME records.
Question and response
Question
dig mail55a.sapsf.eu. NS
Answer
The response has no answer records.
Authority
sapsf.eu. 2650 SOA ns1.sap.net. dns.sap-ag.de. 2019074722 3562 1800 1814400 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0