troubleshooting Question

Certificate issues of Exchange Server 2016

Avatar of Lau Thomas
Lau ThomasFlag for Hong Kong asked on
ExchangeActive DirectoryWindows OS
7 Comments1 Solution13 ViewsLast Modified:


There is a certificate issues of Exchange Server 2016.

Our internal domain of Active Directory (Windows 2016) name is and the external domain name is There are two site A and B connect with leased line.

Site A:
Five Exchange Server 2016 :
Lan subnet :, and (Mailbox and CAS roles)
DMZ subnet :, (CAS role)
All internal and external clients (Outlook, Mac Mail, iPhone, Android and OWA) connect Exchange Server using name

Site B:
Three Exchange Server 2016 :, and
All internal and external clients (Outlook, Mac Mail, iPhone, Android and OWA) connect Exchange Server using name

Existing certificate of Exchange Server is self-sign with internal CA and the self-sign certificate install on all Exchange servers. Certificate include the following subject name:

There are two question:
1. If I want to purchase new certificate for Exchange Server from public, what subject name need to include in the new certificate?
2. In iOS 14.2 or above, when I add the exchange server account on iPhone or iPad, system prompt out a windows say 'Certificate not Trust' and I cannot continue to setup email account. In the past, there is a trust button when the message pop out. When I click the trust button, email account added on iPhone. I search many articles, but there is no solution. Anyone can help?

Best Regards,


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