What Is Error 534 and How To Fix It?

email deliverability checklist cover
Are you frustrated by the pesky “Error 534” message when accessing your email?

Don’t worry, you’re not alone!

This error can be confusing and overwhelming, but with the right information and a bit of problem-solving, you can fix it in no time.

This blog will discuss what Error 534 is, what causes it, and how to fix it.

So, let’s get started and put an end to this frustrating error once and for all!

What Is Error 534?

error 534 infographic
Error 534 is a 5xx error code, which means there has been an issue with the server while attempting to send the email.

This could be due to an issue with the server or configuration, or it could mean that the email address you are trying to send to is incorrect or inactive.

When attempting to connect to a web server that requires a secure connection, a 534 error may occur if the client (such as an FTP client) does not have SSL/ TLS enabled. This is because the server will not accept unsecured communication, and the client must use a secure channel in order to access the server.

When a user attempts to establish a connection without Secure Socket Layer (SSL) encryption, they may experience an error that terminates their connection abruptly and without any indication of how the issue can be corrected.
This error can be unexpected and frustrating, as it does not give users the opportunity to try other means of connecting.

SSL (Secure Sockets Layer) is a security protocol designed to ensure that all data passing between a web server and its users is encrypted, and that only authorized users are able to access the server.

If a user is attempting to connect to an SSL-protected server without using an SSL-encrypted connection, they will likely receive a 534 error until they establish an SSL connection through their FTP client.

It is always important to use an SSL-encrypted connection when accessing a web server, as it provides an added layer of security.

What Causes Error 534?

Error 534 is a type of SMTP error code, which stands for "Authentication mechanism is too weak". It is usually encountered when attempting to send an email and indicates that the sender's email service provider is preventing them from doing so due to weak authentication credentials.

This could be because the email address and/or password being used are incorrect, or because the authentication mechanism used by the provider is not strong enough.

For IBM systems, adding the CHGFTPA parameter to an FTP command may result in the 534 response code being triggered. The parameter should be set to "YES" to enable the sockets layer in the command. If the FTP client SSL parameters are wrong or missing the necessary credentials, this may also be the cause of the 534 response code.

When it comes to establishing a successful SSL connection, it's important to remember that the correct username must be supplied in addition to the password. In particular, some FTP connections, such as IIS-FTP, require the explicit FTP over TLS protocol to be enabled before making the connection attempt.

If this is not done, the connection will fail.

How to Fix Error 534?

Ensuring a successful FTP connection to a remote web server or successful file transfer can be easily achieved by enabling SSL on your FTP client. If you are using commands or have an automated FTP connection in your code, make sure to enable the necessary SFTP flags prior to executing the commands and provide the appropriate username and password.

When troubleshooting the 534 SSL error in an FTP connection, FileZilla is the most popular FTP client and the fix detailed here may be of assistance. However, it should be noted that this same fix may require slight modification depending on the configuration interface of other FTP clients.

  1. Check the error code to determine the exact cause of the error. Error 534 is usually related to an incorrect username or password.
  2. Confirm that the username and password are correct. Double-check any capitalization if you are using a case-sensitive username. Try entering the username and password manually instead of copying and pasting.
  3. Contact your email server administrator or hosting provider for assistance. They can help you troubleshoot the issue and confirm that your account settings are correct.
  4. Check your email client settings. Depending on which email client you are using, you may need to change the authentication settings.
  5. Change your password. If you are unable to log into your email account, you may need to reset your password. Once you have changed your password, update the settings in your email client.
  6. Clear your browser cache and cookies. This can help resolve common authentication issues.
  7. Try using a different browser or device.
  8. Disable any firewalls or antivirus software. This can also help narrow down any compatibility issues.
  9. If all else fails, contact your internet service provider.


Error 534 is a common issue that can occur due to a variety of causes. Fortunately, there are a few easy steps you can take to try and resolve the issue.

First, make sure you are using the correct login credentials and that your firewall is not blocking the connection. Additionally, try clearing your browser's cache and cookies.

If these solutions do not work, you may need to check your email server settings or contact your internet service provider.

With a few simple steps, you can get your email running again and keep sending cold emails.

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