tracking.newsletter2go.com has no MX records.
Question and response
Question
dig tracking.newsletter2go.com. MX
Answer
The response has no answer records.
Authority
newsletter2go.com. 3600 SOA ns1.first-ns.de.newsletter2go.com. postmaster.robot.first-ns.de.newsletter2go.com. 2026021981 14400 1800 604800 3600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0