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SMTP Error 512


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 ( 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 (user@domain.coom instead of You can verify DNS records for the domain with tools such as 1)IntoDNS or 2)MXToolBox.

If the domain name is correct and discover-able, 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
email/troubleshooting/error-numbers/512.txt · Last modified: 2020/06/12 10:18 by Karson N.