Applies to: Exchange Server SE / 2019 / 2016 / 2013 / 2010 | Active Directory Domain Services
When the Microsoft Exchange POP3 service cannot determine the Active Directory site for the server, it can fail with the following error:
No site name is available for this machine.
This is Windows error ERROR_NO_SITENAME (1919 / 0x77F). In most cases, the Exchange server IP subnet is missing from Active Directory Sites and Services or is mapped to the wrong AD site.
In This Article
- 1. Check the Detected AD Site
- 2. Verify the Subnet in Active Directory Sites and Services
- 3. Correct the Subnet-to-Site Mapping
- 4. Validate the Fix
- 5. About the SiteName Registry Value
- 6. Key Takeaways
1. Check the Detected AD Site
Run nltest /dsgetsite on the Exchange server.
If site discovery is working, the command returns the Active Directory site name. If the server cannot determine its site, troubleshoot the subnet mapping before changing Exchange configuration.
2. Verify the Subnet in Active Directory Sites and Services
Open Active Directory Sites and Services and expand Subnets.
- Find the subnet that contains the Exchange server IP address.
- Verify that the subnet is associated with the correct Active Directory site.
- Check for missing, overlapping, or incorrectly scoped subnet definitions.
If the Exchange subnet does not exist, create it and associate it with the correct site. Use the actual network prefix for that location rather than creating an unnecessarily broad subnet.
3. Correct the Subnet-to-Site Mapping
The normal fix is to correct the Active Directory topology, not to force Exchange to use a site manually.
After creating or correcting the subnet object, allow the change to replicate to the domain controllers used by the Exchange server. Then repeat the site discovery test.
4. Validate the Fix
Run nltest /dsgetsite again. It should now return the expected AD site.
After the site is detected correctly, start or restart the Microsoft Exchange POP3 services and verify that they remain running. Current Exchange Server versions still include POP3 support, although the POP3 services are not enabled by default.
5. About the SiteName Registry Value
The original version of this article used the SiteName value under HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Netlogon\Parameters as a workaround.
A configured SiteName can override normal site discovery, but it should not be the first fix for a normal Exchange server deployment. If the server subnet is missing or mapped incorrectly, correct Active Directory Sites and Services instead. Use a manual site override only when there is a specific design or troubleshooting reason for doing so.
6. Key Takeaways
ERROR_NO_SITENAMEmeans Windows could not determine an AD site for the computer.- Use
nltest /dsgetsiteto verify the Exchange server’s detected site. - The preferred fix is a correct subnet-to-site mapping in Active Directory Sites and Services.
- A manual
SiteNameregistry value overrides normal discovery and should not be the default solution.
References
- Microsoft Learn – DsrGetSiteName and ERROR_NO_SITENAME
- Microsoft Learn – POP3 and IMAP4 in Exchange Server
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