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535 Incorrect Authentication Data

This error is commonly seen with mailbox file permissions in cPanel. Root access is required to correct this issue.

You might receive this error under these 2 circumstances:

Incorrect Login Information

Incorrect username format and wrong password may result in this error while sending mails with the incorrect authentication details as the mail server cannot validate the login.

This issue can be resolved by:

  • Making sure that the username format is correct—for example, snappy@hgexample.com (replace 'hgexample.com' with your actual domain name).
  • Changing your email account password.

Corrupted Mail Folder Permissions

This error is often experienced by users who use multiple mail devices and forget to update login details in one of the devices. Also, this may result in when mailbox permissions are changed due to migrations or an account/server update.

VPS/Dedicated Hosting Plan

Users with root access can fix this problem in root WHM by doing the following:

  1. In WHM, locate the Email section in the left-side panel.
  2. Select Repair Mailbox permissions.
  3. Click Proceed.
If you receive this error in Plesk or a Shared or Reseller account, please contact us via phone or Live Chat for further assistance.