Problem
You use the Remote Connectivity Analyzer to test external connectivity for an Exchange 2013/2016/2019 environment but notice that it fails with the following error:
Testing MAPI over HTTP connectivity to server mail.contoso.com
MAPI over HTTP connectivity failed.
Additional Details
Elapsed Time: 11 ms.
Test Steps
Attempting to resolve the host name contexc02.contoso.com in DNS.
The host name couldn’t be resolved.
Tell me more about this issue and how to resolve it
Additional Details
Host contexc02.contoso.com couldn’t be resolved in DNS InfoDomainNonexistent.
Elapsed Time: 11 ms.
What’s strange about the error is that the server FQDN referenced in the message has the FQDN of the internal server name and domain name.
Solution
As much as the error suggests this caused by MAPI over HTTP, you may notice that executing the cmdlet:
Get-MapiVirtualDirectory | FL ServerName, *url*, *auth*
… would reveal that the configuration for the external MAPI Virtual Directory is already configured with the appropriate URL.
Executing the cmdlet:
Get-OrganizationConfig | fl identity,*mapi*
… will also indicate that MAPI over HTTP is enabled.
What typically causes this issue is if Outlook Anywhere has not been configured. You can review the settings on each of the servers either by executing the following cmdlet:
Get-OutlookAnywhere | FL Identity,*Host*,*requireSSL*
… or navigating to the server properties’ Outlook Anywhere section, which would likely have the internal server’s FQDN as that is the default:
Either adjust the configuration in the EAC for each server appropriately or use the following cmdlet to configure the settings:
Set-OutlookAnywhere -Identity:”<serverName>Rpc (Default Web Site)” -DefaultAuthenticationMethod NTLM -InternalHostname <internalFQDNURL> -InternalClientsRequireSsl $true -ExternalHostname <externalFQDNURL> -ExternalClientsRequireSsl $true -SSLOffloading $false
The Remote Connectivity Analyzer should return successful results once this has been corrected.
