Dear Support Team,

I would like to ask you about Exchange server 2013. I created a new accepted domain (new SMTP) when i tried to configure outlook client that don't join domain for connect to new SMTP, it is alert message "An encrypted connection to your mail server is not available. click Next to attempt using an encrypted connection.". but client can access new SMTP in new accepted domain by web base So can you tell me something about this problem and please lets me know as soon as ! 

Best regards,

Sokhom

Hi there,

So you have created a new SMTP domain, if this is the primary email domain for some of your users now, which it sounds like it is - have you configured the appropriate autodiscover record in external DNS for the non domain joined external user to be able to use via a DNS lookup and added the autodiscover record to your certificate, or created an autodiscover redirect DNS

Hi Sokhom,

From your description, I recommend you use the Remote Connectivity Analyzer to test autodiscover at first. What's more, use the following cmdlet to make sure that MAPI is enabled.

Get-CASMailbox user@contoso.com |fl MAPI*

Hope this can be helpful to you.

Best regards,