Exchange Server 2010 to 2016 mailflow problem

whenz used Ask the Experts™
I installed a new Exchange Server 2016 in an existing Exchange Server 2010 environment.  I am now having trouble to send/receive mails between the Exchange Servers.  There is no Firewall between the both Servers, they are in the same LAN.

I am going nuts, do you have any idea why the mailflow does not work?
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HI whenz,
Please make sure Exchange server authentication is enabled
test.JPGAnd make sure your internal FQDN is set properly.
test.JPGGet-clientAccessServer | fl Name,AutoDiscoverServiceInternalUri
Get-OabVirtualDirectory |  fl Server,Name,internalurl,externalurl
Get-WebServicesVirtualDirectory | fl Server,Identity,internalurl,externalurl
Get-EcpVirtualDirectory |  | fl Server,Identity,internalurl,externalurl
Get-OwaVirtualDirectory | fl Server,Identity,internalurl,externalurl
Get-ActiveSyncVirtualDirectory | fl Server,Identity,internalurl,externalurl
Keep External URLs null in Exchange 2010 and Set the IIS authentication to BASIC + NTLM in Exchange 2010. This is for OutlookAnywhere
Read this for more details.

Use this URL to set URLs
Please restart Transport service after the change.
Hani M .S. Al-habshiContributor as IT Expert

Go to Server Configuration >> Hub Transport >>Default Receive connector >> Properties >>Authentication

 Enabled   Exchange server authentication

Go to Server Configuration >> Hub Transport >>Default Receive connector >> Properties >>General
FQDN  should be the host bios name example: (Local_Server_Name


Thank you for the hint.  I checked these settings, and everything seems to be correct.  I have the following scenario:

 - I send an email form external to a mailbox (lets call this mailbox Adrian) which is hosted on the exchange 2016 server
 - Adrian's mailbox has a mail forward to another external mail address, let's say
 - When sending an email from an external address to Adrian, this mail does not arrive in the Mailbox of Adrian BUT it gets forwarded to
any other idea how to proceed?

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Technical Consultant

1. On the server you are trying to send TO, check the properties of the Default receive connector and ensure ‘Exchange Server authentication’ is selected.

Exchange Server Authentication

2. On the server you are trying to send TO, If you have a connector configured to ‘relay’ mail, make sure that the server(s) or network specified DOES NOT include the IP address of the server you cannot send FROM. Also Make sure on the authentication tab ‘Exchange Server authentication’ is NOT selected.

Relay Mail Connector

Hani M .S. Al-habshiContributor as IT Expert

this mail does not arrive from external

1-You should recheck Split DNS Records ,A record , ,MX record,Static IP DNS Revers Name..etc  (use )

2-Recheck your Receive Connectors .

3-Use  and give us the report


Thanks Ajun, it was indeed a relay receive connector where the exchange server was in the ip range.  i removed that ip range and now it works. you are my hero!!!!

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