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How to Fix Email Error 550 5.4.312: DNS Query Failed
Question details
The user needs to resolve an email bounce-back error indicating that a message expired because the DNS query for the recipient's domain failed.
- Product
- Email Client
- Device & OS
- not provided
- Scenario
- Sending an email to a specific recipient domain and receiving an automatic non-delivery report.
- Observed behavior
- The email fails to deliver and returns Error 550 5.4.312, stating that the mail server could not resolve the recipient domain's DNS or MX records.
Ensure you have the exact recipient email address and domain name handy, and confirm that your own internet connection is stable before troubleshooting server-side DNS issues.
Verify and Validate the Recipient's MX Records
Use this solution to diagnose if the recipient's domain has misconfigured, unavailable, or missing Mail Exchanger (MX) records, which is the primary cause of this error.
Error 550 5.4.312 typically points to a server-side routing issue where the sender's mail server cannot locate the recipient's mail server due to faulty DNS resolution.
Open your web browser and navigate to a free DNS verification website, such as MXToolbox.
Type the domain name of the recipient (the portion of the email address located after the '@' symbol) into the primary search bar.
Click the 'MX Lookup' button to query the domain's DNS host and check if valid mail server records are returned.
Review the test results. If the MX records are missing, invalid, or fail the check, the recipient's IT administrator must update the DNS settings at their domain hosting provider.
Confirm Domain Spelling and Contact the Administrator
Use this approach if you are the sender and do not have administrative access to fix the recipient's external DNS settings.
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Frequently Asked Questions
What exactly does Error 550 5.4.312 mean?
This error means that your email server could not route the message to the intended recipient because it failed to resolve the recipient domain's DNS records, specifically the MX (Mail Exchanger) records, causing the delivery attempt to expire.
Can updating my SPF or DKIM settings fix this error?
No. While SPF and DKIM are important for authenticating emails and preventing them from being marked as spam, they do not resolve the underlying MX lookup failures or DNS routing issues responsible for Error 550 5.4.312.
Who is responsible for fixing Error 550 5.4.312?
The IT administrator of the recipient's domain is typically responsible for resolving this issue. They must ensure their DNS host is fully operational and that their MX records are correctly published and propagated across the internet.
