How to troubleshoot 454 4.7.1 Relay access denied webmail error?

This 454 4.7.1 error usually happens while sending to and receiving the mails from external domains.

Error:

454 4.7.1 user@domain.com: Relay access denied

The mail client connects to the sender’s mail server and attempts to deliver the mail to the recipient.

The recipient can be within the same mail server or in any external mail server. But most mail server require the mail account has to authenticate itself correctly, inorder to connect to it to send mails.

Error 454 4.7.1 is shown in the email logs and bounce message to users, usually when they send, forward or receive mails.

You can see this error in Roundcube and Squirrelmail with the below configuration.

Roundcube has a configuration file ‘config.inc.php’, which is used for the SMTP configuration settings. If the settings provided in this section go wrong during the setup, it will give 454 error.

In Squirrelmail, the configuration file is ‘config.php’ and is configured using the Perl script ‘conf.pl’ We have seen that webhosts who have not configured it correctly, have users facing error 454 while sending mails.

The parameters we configure for smooth SMTP functioning are:

1) SMTP server for outgoing messages.
2) SMTP authentication settings for users.
3) TLS/SSL settings for secure email delivery.
4) SMTP port for incoming and outgoing mails.

Once the configuration of Roundcube or Squirrelmail or other webmail clients are properly done, users can send emails without any errors.