SMTP Error 512
Description: A DNS error: the host server for the recipient’s domain name cannot be found.
What does this mean?
The email recipient’s email address (firstname.lastname@example.org) is using a domain name that can not be found.
How to fix SMTP Error 512?
This is commonly due to misspelling in the recipient’s email address such as (email@example.com instead of firstname.lastname@example.org). You can verify DNS records for the domain with tools such as IntoDNS or MXToolBox.
If the domain name is correct and discoverable, it’s likely due to your mail server’s network configurations or resolv.conf.
SMTP Error 512 Examples
SMTP Error 550 5.1.2 Host unknown – host cannot be found