The "Unroutable mail domain" error means the mail server cannot determine where to deliver email for a specific domain. This typically happens when a domain's DNS records are missing, expired, or not pointing to a valid mail server.
Missing MX records or expired domain
If you see this error when sending to a specific address, that domain either has no MX (mail exchange) records in DNS, or the domain has expired and DNS has stopped resolving. If you see it for your own domain, your MX records need to be set up correctly.
01. Error When Sending TO an Address
If you are sending email to someone and your message bounces with "Unroutable mail domain," the problem is on the recipient's side:
- Their domain expired - The domain no longer resolves in DNS
- Their MX records are missing - The domain exists but has no mail exchange records
- Typo in the address - Double-check the domain part (after the @) for spelling errors
You cannot fix this on your end. Contact the recipient through an alternative channel and let them know their domain's email is not working.
02. Error for Your Own Domain
If emails to your domain are bouncing with this error, check your MX records:
- Log into cPanel > Email > Email Deliverability
- Check for warnings about MX records
- If records are missing, click "Repair" to let cPanel set the correct MX records automatically
You can also check manually in cPanel > Domains > Zone Editor. Your MX record should point to mail.yourdomain.com (or the server hostname) with priority 0.
For more on MX records, see How to Change Your MX Records.
If you recently pointed your domain to Ultra Web Hosting, the MX records may not have propagated yet. DNS changes can take up to 48 hours. See DNS Changed But Site Not Showing.
03. Sending Between Accounts on the Same Server
A less common cause: if you are sending from one email address on your hosting account to another address on a domain that is also on the same server, but that domain's email is handled by an external service (like Google Workspace), the server may try to deliver locally instead of routing externally. This is called the "local delivery" issue.
If this is your situation, open a support ticket and we can adjust the mail routing for the affected domain.
Email Delivery Issues?
If your email is bouncing or you are seeing routing errors, open a ticket with the full bounce message.
Open a Support TicketFrequently Asked Questions
What does Unroutable mail domain mean?
The mail server cannot determine where to deliver email for a domain, usually because the domain's DNS or MX records are missing, expired, or not pointing to a valid mail server. The server has no route to hand the message off.
How do I fix an Unroutable mail domain error when sending?
Check the recipient domain's address for a typo, and if it is correct, the recipient domain's DNS or MX records are likely broken on their side. If it is your own domain, confirm your MX records point to our mail server and that the domain has not expired.
Why do I get this sending to my own domain?
Usually your domain's MX records are missing or point elsewhere, or the domain is set up in a way the server does not recognize as local. Confirm the MX records in DNS point to our mail server, and open a ticket if the domain should be local but is not routing.
Why does mail between two accounts on the same server fail as unroutable?
This happens when a domain's DNS points its mail elsewhere while it is also hosted here, so the server is unsure whether to deliver locally or remotely. Make sure the MX records match where the mailboxes actually live, and contact support to align the mail routing if needed.
Quick Recap
- "Unroutable" means DNS cannot find a mail server for that domain
- Sending to others - Their domain is expired or has no MX records
- Your own domain - Check MX records in cPanel > Email Deliverability
- Click "Repair" if cPanel flags MX issues
- Allow 48 hours after DNS changes for propagation
Understanding email routing · Last updated November 2026 · Browse all Email articles
