_spf.herold.at has no MX records.
Question and response
Question
dig _spf.herold.at. MX
Answer
The response has no answer records.
Authority
herold.at. 3600 SOA dns2.telekom.at. domainadmin.a1.net. 2026021900 10800 3600 1814400 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0