In: Add an MX record
i got same problem too. i can't response from https://www.checktls.com/TestReceiver
how can i use with outlook or same external software? i added my all dns on cloudflare and everything is working, but mail server doesnt work when i add my mail informations into in softwares. also mails working in server(phpmail).
thank you
do alternative:
vultr.com