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,” and it can appear for several different reasons.
For example, it can be a simple matter of email client misconfiguration. Your SMTP server will only process your outgoing emails if it’s sure the application is authorized to access your account. If your email client is not configured to present your username and password whenever it connects to the SMTP server, you will receive a “550 relay not permitted” error. Modifying the account settings on your client application should fix the issue.
ScalaHosting customers can find the correct IMAP/POP3/SMTP settings in the Welcome Email they receive after activating their account. It is also available in the My Details > Email History section of their Client Area.
In another scenario, the problem is a bit more complicated, and addressing it is not as straightforward.
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 mail 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.