stardust.sirsi.net has no MX records.
Question and response
Question
dig stardust.sirsi.net. MX
Answer
The response has no answer records.
Authority
sirsi.net. 1800 SOA coco.ns.cloudflare.com. dns.cloudflare.com. 2398065285 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0