spf.sealmail.co has no MX records.
Question and response
Question
dig spf.sealmail.co. MX
Answer
The response has no answer records.
Authority
sealmail.co. 3600 SOA nameserver01.mi.com.co. hostmaster.sealmail.co. 2025122901 10800 3600 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0