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 two 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:
- Ensuring that the username format is correct. For example, you should enter the complete username, firstname.lastname@example.org (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 on one of the devices. Also, this may result when mailbox permissions are changed due to migrations or an account/server update.
A user should have root access to fix this problem in the root WHM (rWHM), which means you should be on VPS/Dedicated hosting account.
To set mail folder permissions in WHM:
- Log in to WHM.
- Look for the Repair Mailbox Permissions section. The quickest way is by typing the keyword on the Search box on the left-side panel.
Alternatively, you can use the Search box at the top.
- Select Repair Mailbox Permissions.
You can also manually locate and expand the Email section on the left-side panel, then click Repair Mailbox Permissions from the list.
- Click Proceed.
- The system will rebuild the mail databases and fix permissions.
- Once done, check your emails again.