Reliable email communication depends on many components. Inevitably, sometimes, one of them breaks and people trying to send and receive emails instead see error messages that are not always as descriptive as you would hope.
One of these errors is “550 relay not permitted.”
If users trying to send you emails receive a “550 relay not permitted” error, it likely means that your mail server has received the message but is not configured to work with your domain.
If your mail server processes every email coming its way, you would have the so-called open relay setup. Pretty much all mail servers used to be built this way in the early days of the internet, but countless attacks from spammers and hackers made the configuration obsolete.
To protect users, every modern mail server now has its own list of domains it processes emails for. If your domain isn’t on your mail server’s list, people trying to send emails will get a “550 relay not permitted” error. It’s not a particularly common problem, but it can occur, especially if you’ve recently changed your mail server.
If you stumble upon this sort of issue with your ScalaHosting account, be sure to contact our technical support experts, who will help you resolve it.