fix smtp error (535) authentication failed

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Everyone expect mails to work flawlessly, but that doesn’t always work.
Occasionally, mail servers may reject emails with some strange errors, such as “SMTP Error (535): Authentication failed”


we often get requests from customers to tell them a fix for this SMTP Error.

Today, we’ll see how to fix SMTP Error (535)

What is SMTP Authentication?

Mail client like Outlook uses SMTP (Simple Mail Transfer Protocol) to send messages. Later, to download emails, the usage of email client like POP or IMAP can be used.

But, for any reason, if the authentication fails, mail client like Outlook generates an appropriate error message.
“SMTP Error (535): Authentication failed” error is usually related to the bad user email settings in Microsoft Outlook.

That’s why, Email client configuration always need special attention. Now, let’s see the reasons behind this error.

Causes For the “Error 535: Authentication failed”

1. Incorrect Username and Password

When the username and password entered in the Email client are incorrect, it ends up in Error 535.

also, using rong mail server can also cause this problem.

Usually, such mismatch in email login and password will be recorded in the mail server logs. This helps greatly in finding the exact email account with problems.

2. Account Disabled

Similarly, at times account can be disabled because of reasons like payment dues or spamming issue. This will also result in SMTP Error (535): Authentication failed.
So, it’s worth to login to the control panel and check the status of the customer account as well as the email account.

3. SMTP Authentication

If your email client do not have SMTP authentication turned ON, it can also result in error.


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