What the message looks like
Host or domain name not found. Name service error for name=example.com type=AAAA: Host not foundHost or domain name not found. Name service error for name=example.com type=MX: Host not found, try again
What it means
The sending server looked up the recipient's domain in DNS to find its mail server, and found nothing it could deliver to. The domain doesn't exist, or it has no MX record and no address record to fall back on. The standard name for this status is "unable to route".
There's no reply code because the receiving server was never contacted. The sending server's own report, often starting X-Postfix;, is all you get.
If the message ends in "try again", the status is 4.4.3 instead. That means the DNS lookup itself failed for now, so the sending server keeps retrying.
Common causes
- A typo in the domain, such as
gmial.com. - The domain has expired, or was never registered.
- The domain exists but has no mail set up, as with many domains used only for a website.
- For the temporary
4.4.3version, the domain's DNS servers aren't responding or are misconfigured.
If you're the recipient
Check the domain in the address you gave out. If it's your own domain, check it hasn't expired, and that it has MX records pointing to your email provider.
If you're the sender
Check the address for typos. If it looks right, look the domain up with a DNS tool. If it has no MX records, nothing will reach it until the owner sets them up.
If you use addy.io
If this appears on your Failed Deliveries page for a forwarded email, the domain of your recipient address can't receive mail. Check the domain is still registered and set up for email, or add a different recipient.
If it happens when you reply or send from an alias, check the address you're sending to.