These are the DNS Records for:
MX-03.DE.MAIL.MUELLER.DE
Type
Host
Class
TTL
IP
A
mx-03.de.mail.mueller.de
IN
300
116.202.187.194
Type
Host
Class
TTL
TXT
TXT
mx-03.de.mail.mueller.de
IN
300
v=spf1 include:_spfa.mueller.de -all