1. whois
sukunet.official.ec. 60 IN CNAME cname.thebase.in. cname.thebase.in. 60 IN CNAME thebase.in. thebase.in. 60 IN TXT "facebook-domain-verification=qksa5v7wmomvg8amq7yet9o0p4pzrp" thebase.in. 60 IN TXT "google-site-verification=bjxhHupfNNKHTgFsm5agaQf8ezhtSthZc4YrEsJseYI" thebase.in. 60 IN TXT "v=spf1 include:amazonses.com include:_spf.google.com include:mail.zendesk.com -all"
2. history
https://thebase.com/inquiry/sukunet-official-ec
折返しのメールが受信できるように、ドメイン指定受信で「thebase.in」と「sukunet.co.jp」を許可するように設定してください。