Troubleshoot sendmail stat=deferred name server host name lookup failure with clear DNS checks, causes, and solutions. Our Live Support Team is always here to help you.
Sendmail stat=deferred name server host name lookup failure Explained
When you see the error sendmail stat=deferred name server host name lookup failure, it usually means your server is struggling with DNS while trying to deliver anemail. Instead of discarding the message, Sendmail keeps it in the queue and retries later. Let’s go straight into what this error means, why it happens, and how to sort it out.
Breaking down the error
- stat=deferred: This means delivery is postponed. The server hasn’t rejected the message, it just can’t send it right now.
- name server host name lookup failure: The mail server is unable to resolve the recipient’s hostname or the related DNS record.
Common reasons behind it
There are several possible triggers when this error shows up:
- DNS Configuration Issues
The DNS setup on the Sendmail server may be wrong. Check if the server points to valid, working DNS servers.
- DNS Server Unavailability
If the DNS server itself is down or slow, Sendmail cannot perform lookups.
- Incorrect DNS Records
Missing or incorrect MX records for the recipient’s domain will stop Sendmail from finding where to deliver the email.
- Firewall or Network Restrictions
Firewalls may block DNS queries, or network issues may prevent communication with DNS servers.
- Domain Name Resolution Order
The order in which the system resolves hostnames matters. If /etc/hosts is checked before DNS and no valid entry exists, lookups will fail.
- Local Hostname Configuration
If the sending server’s hostname is misconfigured, it can cause lookup failures. Ensure the hostname is set correctly.
- Domain-Specific Issues
Sometimes the problem lies with the recipient’s domain itself. If their DNS setup is broken, delivery will fail.
How to troubleshoot and resolve
To deal with this, go through these checks:
- Verify that your server’s DNS configuration is accurate.
- Make sure the DNS servers you use are reachable and operational.
- Double-check DNS records, especially MX records, for the recipient’s domain.
- Review firewall settings and allow DNS queries through.
- Confirm that your server’s hostname is correctly configured.
- Test DNS resolution with command-line tools like:
nslookup example.com
dig example.comBoth tools will show whether DNS queries are resolving properly.
[If needed, Our team is available 24/7 for additional assistance.]
Conclusion
A misconfigured hostname on the sending server causes lookup failures, so set the hostname correctly. With proper hostname setup and working DNS records, Sendmail will be able to deliver mail without putting it on hold.
0 Comments