SMTP Error 535 Authentication Failed

When you attempt to log in, you are more likely to encounter an authentication failure error on your server. The error typically happens when you attempt to log in using the incorrect username or password. The username and password you entered in the username or password field will not be accepted by your mail server, which will result in a failed authentication attempt.

Our technical support team receives a lot of requests to resolve authentication failure errors as a provider of server management services. With the help of this blog, we hope to clarify the various reasons why the error occurs as well as how our server engineers resolve the "SMTP Error 535 Authentication Failed" message.

Reasons: "SMTP Error 535 Authentication Failed"

The mail client employs the Simple Mail Transfer Protocol to send the messages. The server will generate an error message if it discovers any improper authentication. Different error messages are displayed by the server based on the email program. The server might occasionally not show any error messages. The following are a few typical causes of the SMTP error 535 authentication failed message:

• Inaccurate Username or Password

You may receive the message "SMTP error 535 authentication failed" if you accidentally enter the incorrect username or password into your program. Typically, everyone logs in to your mail server using the same username and password as your email address.

Some SMTP servers request a different set of credentials from your email account. Server security can be preserved in this manner. If you require any additional help, you can speak with the administrator of your mail server.

• Disabled Account

Your account may be disabled temporarily or permanently due to problems like spamming and unpaid invoices. The message "authentication failed" may be caused by a disabled account. Therefore, you should check the status of your account to make sure it is active. Please get in touch with your server's support staff if you have any problems.

• Connection Encryption

For some servers, you might need to enable an SSL/TLS-encrypted connection. An SMTP error 535 authentication failed message could be received if this option has been disabled.

• Authentication Methods

Your mail server may display an SMTP error if you use authentication methods that it does not support. You must check the status of your account to fix the IP-based authentication that has been disabled or has expired. SMTP error 535 authentication failed messages can be sent even though IP-based authentication is thought to be a rare error.

Resolving the "SMTP Error 535 Authentication Failed" Message

• You should first login to your control panel and see what the status of your account is right now. Normally, if there are any problems with your account, you will be notified.

• Verify the provided username and password before logging into your mail server. It's crucial to change the login information to something more secure, and you should remember to do so the next time you log in.

• The IP addresses that repeatedly attempt to log into your account should be blocked. You can stop them from trying to log in again by blocking the IP address at the firewall on the server.

• Enable server-side and client-side SMTP authentication.

Making SMTP authentication available in Plesk:

• Enter your credentials to access the Plesk control panel.

• Choose Mail server Settings from Tools & Settings.

• Enable SMTP services is selected under Relay Options.

If you are having trouble solving the problem on your own, you can contact the Plesk server management service provider.

Enabling SMTP authentication in cPanel:

SMTP authentication is by default disabled in WHM. As a result, you might have to enable authentication on your own. You can use the method listed below for this purpose.

• Select Service Configuration under WHM navigation.

• select the Service Manager.

• You may now select the Antirelayd box.

You can get more help by contacting your cPanel server support company.