cu0513c.smtpx.saremail.com has no MX records.
Question and response
Question
dig cu0513c.smtpx.saremail.com. MX
Answer
The response has no answer records.
Authority
saremail.com. 300 SOA ns1.sarenet.es. dnsmaster.sarenet.es. 2025112407 86400 7200 2592000 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0