We deploy our Smartermail server with only one hostname ex: mail.mailsample.com and configure hosted domains with that hostname in domain options. Therefore I checked autodiscover setings in each domain and xml refers to desire hostname mail.mailsample.com. Then I create required DNS records autodiscover to point to mail.mailsample.com in each hosted domain. With Microsoft connectivity tool it fails many checks and pass TCP SRV test, but Outlook 2019 fails autodiscover. I try Mozilla Thunderbird and fails autodiscover too. Then inside Smartermail IIS site I configure *:443(https) and http://mail.mailsample.com:80 bindings, inside default IIS site I configure *:80(http) binding and a redirect to mail.mailsample.com. Now Microsoft connectivity tool passes HTTP redirect test but Outlook 2019 continue fail and Mozilla Thunderbird sucess autodiscover.

I found that Google uses imap.gmail.com and smtp.gmail.com in SSL as servers to their hosted client domains like companydomain.com.

Anyone can help deploy autodiscover for Outlook 2019?

Tahnks