Overview
The “550 Host Unknown” error typically occurs when trying to send an email, but the mail server cannot deliver it because it can’t identify the recipient’s mail server. In simpler terms, the sending server doesn’t know where to deliver the email. This is most often a DNS-related issue, meaning that the Domain Name System (DNS) is not correctly routing the email.
Causes
This error can originate from the recipient’s email domain or your From Email address domain. Below are the main causes of the error:
- The domain’s DNS records are misconfigured or incomplete
- The MX (Mail Exchanger) records for the domain are missing or incorrect
- Recent changes to DNS settings haven’t fully propagated
- The domain has expired or is no longer registered
Solution
Most email service providers require users to add one or more DNS records when setting up their SMTP plugin. Before proceeding, make sure you’ve added the provided DNS records to your site’s DNS settings.
Note: Check out our DNS records tutorials for steps on adding DNS records for most domain registrars.
Since this error is DNS-related, we suggest checking your domain’s DNS settings and that of the recipient. Here are some areas to check as you troubleshoot:
- Verifying that the domain in the recipient’s email address is spelled correctly
- Checking the DNS configuration for the recipient’s domain, especially the MX records
- Waiting for 24-48 hours if DNS changes were recently made, as propagation can take time
- Confirming with the recipient that their domain is active and properly configured
That’s it! Now you know how to troubleshoot and resolve the ‘550 Host Unknown: Incorrect DNS settings’ error.
Want to explore available email service providers WP Mail SMTP supports? Be sure to check out our complete guide to WP Mail SMTP mailers.