Troubleshoot: UM voice mails not submitted to Hub Transport

After you have set up the Exchange Server 2007 UM role in a lab or in production and want to test Auto Attendant functionality by leaving voice mails for one or more users, you may experience that the Auto Attendant plays the greeting and asks for your message but the user doesn't receive anything although everything seems fine.

Voice mails are in fact recorded and will queue up in this directory: C:\Program Files\Microsoft\Exchange Server\UnifiedMessaging\voicemail

This situation can be identified by the following warning in the Application Event log:

Event Type:      Warning
Event Source:    MSExchange Unified Messaging
Event Category:  UMCore
Event ID:        1185
Date:            17-12-2007
Time:            16:32:06
User:            N/A
Computer:        <Servername>
The Unified Messaging server was unable to submit a message to Hub Transport server "<Servername>" because the following error occurred: The Unified Messaging server failed to authenticate to the SMTP server: The specified target is unknown or unreachable.

There can be multiple reasons for this, some of these are listed below.


If Service Principal Names (SPN) are not registered correctly for your Hub Transport Servers SMTP service, the UM service may fail to identify a usable receive connector and fail to deliver the voice mail.

One scenario where SPN's are registered incorrectly is if receive connectors have been installed on multiple servers (e.g. if the Exchange Organization used to be Exchange Server 2003 and mailboxes and services were migrated to Exchange Server 2007).

To verify that local SPN registration is correct, first run:

setspn -L <Servername>

This will list the locally registered SPN's, there should be only two "SmtpSvc" SPN's:


The more likely situation is that another server that no longer has a receive connector installed still have a "SmtpSvc" SPN registered.

To search Active Directory for orphan SPN's, use LDP; connect and bind to AD and press Ctrl-S for the search dialog.

Base Dn: DC=domain,DC=ext
Filter: servicePrincipalName=smtpsvc*

This will result in a list like this:

Getting 2 entries:
>> Dn: CN=OLDSERVER,CN=Computers,DC=domain,DC=ext
    5> objectClass: top; person; organizationalPerson; user; computer;
    1> cn: OLDSERVER;
    1> distinguishedName: CN=OLDSERVER,CN=Computers,DC=domain,DC=ext;
    1> name: OLDSERVER;
    1> canonicalName: domain.ext/Computers/OLDSERVER;
>> Dn: CN=NEWSERVER,CN=Computers,DC=domain,DC=ext
    5> objectClass: top; person; organizationalPerson; user; computer;
    1> cn: NEWSERVER;
    1> distinguishedName: CN=NEWSERVER,CN=Computers,DC=domain,DC=ext;
    1> name: NEWSERVER;
    1> canonicalName: domain.ext/Computers/NEWSERVER;

Now use ldp or adsiedit to further drill down on the OLDSERVER object, I find using adsiedit easier as it allows for instant editing if required. If you're not familiar with editing directly on AD objects, get assistance from someone who is!

List the content of servicePrincipalName and verify that no SmtpSvc entry exists if no SMTP service is running on the machine and verify that only the servers' own name is listed for any SPN.

After removing any faulty SPN registrations; restart the Microsoft Exchange Transport Service on your Hub Transport Server. Then restart Microsoft Exchange Unified Messaging to pick up voice mails in the queue.


Exchange UM submits the mails with voice content by using TLS, therefore UM may be unable to authenticate to the receive connector on the Hub Transport Server if the servers use the self signed certificate that Exchange supplies upon installation.

Verify what certificates are installed by running:

Get-ExchangeCertificate | ft services,thumbprint,isselfsigned -auto

The result will look somewhat like this:

                Services Thumbprint                               IsSelfSigned
                -------- ----------                               ------------
IMAP, POP, UM, IIS, SMTP 1234567890ABCDEF1234567890ABCDEF12345678         True

As you can see the only existing certificate is self signed.

Create new certificates for all Exchange Servers in the organization by running this cmdlet:

New-ExchangeCertificate -GenerateRequest -domainname <Server FQDN>, <Server NetBIOS name>[, Server Alias] -FriendlyName <Server FQDN> -privatekeyexportable:$true -keysize 1024 -path c:\certreq.txt

Submit the request file to your internal CA (depending on your Public Key Infrastructure) and save the resulting certificate file as c:\certnew.cer

Then import the certificate by running this cmdlet:

Import-ExchangeCertificate -path c:\certnew.cer | Enable-ExchangeCertificate -services IIS, POP, IMAP, UM, SMTP

Verify again what certificates are installed with Get-ExchangeCertificate.

The result should look like this:

                Services Thumbprint                               IsSelfSigned
                -------- ----------                               ------------
IMAP, POP, UM, IIS, SMTP ABCDEF1234567890ABCDEF1234567890ABFDEF12       
     IMAP, POP, UM, SMTP 1234567890ABCDEF1234567890ABCDEF12345678        

As you can see, you now have a non self signed certificate in the certificate store. Remove the self signed certificate by running:

Remove-ExchangeCertificate 1234567890ABCDEF1234567890ABCDEF12345678

Restart Microsoft Exchange Transport and Microsoft Exchange Unified Messaging services and verify if voice mails are delivered.

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