mailservers.supportbee.com has no AAAA records.
Question and response
Question
dig mailservers.supportbee.com. AAAA
Answer
The response has no answer records.
Authority
supportbee.com. 1800 SOA eva.ns.cloudflare.com. dns.cloudflare.com. 2397293884 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0