spf.customer.artelis.net has no MX records.
Question and response
Question
dig spf.customer.artelis.net. MX
Answer
The response has no answer records.
Authority
artelis.net. 3600 SOA ns1.artelis.net. hostmaster.artelis.net. 2026022701 28800 3600 1728000 3600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0