Symptoms

You receive a bounce reply from cPanel with the error message "550 5.1.1 User doesn't exist". You have an email forwarder in place. The email is delivered to the email address the email forwarder forwards to.

You may receive a bounceback message that is similar to the following:

LMTP error after RCPT TO:<admin@domain.tld>: 550 5.1.1 <admin@domain.tld> 
User doesn't exist: admin@domain.tld

Problem

This problem occurs when the email address was previously used as a mailbox and then deleted. cPanel will leave some files in place at the following location (replace values that match the mailbox):

/home/username/mail/domain.tld/admin

This file path references "admin@domain.tld". As another example, jerry@example.com would have the file path: /home/username/mail/example.com/jerry.

Since this path exists but a mailbox does not, a bounceback error is delivered to the sender as the mailbox cannot be found.

Solution

To resolve this problem, delete or rename the directory of the former mailbox that is causing the bounceback errors. For example, use the cPanel File Manager to rename the directory. You can also delete the folder entirely.

Example: delete /home/username/mail/example.com/jerry

Do not delete the "example.com" directory or any other directory contained within it.