a.mail-forward.sonic.net has no MX records.
Question and response
Question
dig a.mail-forward.sonic.net. MX
Answer
The response has no answer records.
Authority
sonic.net. 86400 SOA a.auth-ns.sonic.net. hostmaster.sonic.net. 2026021801 10800 3600 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0