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How to fix error “454 4.7.1 Relay access denied” in Postfix mail servers

How to fix error “454 4.7.1 Relay access denied” in Postfix mail servers

454 4.7.1 <>: Relay access denied

This is a commonly seen email failure error by web hosts, website owners and server owners who run Postfix mail server. 454 error usually happens while sending to and receiving from external domains.

In our role as Hosting Support Engineers for web hosting companies, we handle many such mail errors and fix them. Here, we’ll see what causes “454 4.7.1 Relay access denied” error and how we fix it.

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What causes “454 4.7.1 Relay access denied” in Postfix servers

In mail delivery process, a mail client such as Outlook, Squirrelmail, etc. is used by the sender to send an email. 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 is shown in the email logs and bounce message to users, usually when they send, forward or receive mails in Postfix mail servers. There are 2 main causes for this error.

  1. If the mail is attempted to send to an external mail server without proper authentication, the sending mail server will reject the mail with the error “454 4.7.1 Relay access denied”.
  2. This error message is also seen due to improper configuration settings of Postfix, such as relaying and recipient settings.
Jan 22 10:25:14 user postfix/smtpd[2257]: NOQUEUE: reject: RCPT from unknown[***.***.***.***]: 454 4.7.1 <>: Relay access denied; from=<> to=<> proto=ESMTP helo=<S>


454 471 relay access denied

Email delivery process


Here, we’ll see how to fix the error “454 4.7.1 Relay access denied” that users get while using Postfix servers for email delivery.


1. How to fix “454 4.7.1” in mail clients – Outlook, Squirrelmail, Thunderbird and Roundcube

Unless specifically excluded from authenticating to SMTP mail server by adding the IPs to the trusted network, Postfix does not allow anyone to relay through the mail server.

Incorrect settings in the email client can cause mail delivery to fail, when the mail account tried to send a mail to an external domain from a Postfix server, without proper authentication.

So the first thing we do when users report 454 error is to check and confirm why the error happened in that server. Checking the mail logs, bounce message and confirming with other email clients help to pinpoint if the issue is with the mail client or server settings.

While Outlook and Thunderbird are user specific email clients and have to be configured by individual users, webmail such as Squirrelmail and Roundcube are installed and configured server wide.

If any configuration mistake happens in the installation process of 3rd party software such as Roundcube and Squirrelmail, no user from the server would be able to send mails using these webmail clients.

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How to fix “454 4.7.1 Relay access denied” in Roundcube and Squirrelmail

Roundcube has a configuration file ‘’, 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 ‘’. We’ve seen that webhosts who have not configured it correctly, have users facing error 454 while sending mails.

At Bobcares, our Web Support Specialists have expertise configuring 3rd party software such as Roundcube and Squirrelmail for our customers who are web hosts.

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.

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How to fix “454 4.7.1 Relay access denied” in Thunderbird, Outlook Express and Microsoft Outlook

In cases where we notice that the issue is not a server wide one, but specific to the user account, it is obvious that the error has happened due to incorrect email client settings of that user.

Some of the commonly used email clients are Outlook Express, Microsoft Outlook, Thunderbird and so on. The settings for SMTP authentication, SMTP server and security varies in each mail client.

We provide the end users with the step by step details to configure their email clients, which prevents email delivery failures with the error “454 4.7.1 Relay access denied”.

454 471 relay access denied error

Mail client configuration settings for SMTP

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