3b._spf.dhl.com has no MX records.
Question and response
Question
dig 3b._spf.dhl.com. MX
Answer
The response has no answer records.
Authority
dhl.com. 300 SOA ns4.dhl.com. netmaster.dhl.com. 2016118530 10800 3600 604800 300
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0