activate.spectrum.net has no MX records.
Question and response
Question
dig sdptpsi.g.charter.com. MX
Answer
The response has no answer records.
Authority
G.CHARTER.COM. 60 SOA GSLB.G.CHARTER.COM. HOSTMASTER.G.CHARTER.COM. 2025093002 10800 3600 604800 60
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0