cPanel bug in checking incoming email has a valid sender account

Stephen Hare

Nov 12, 2017
cPanel Access Level
Root Administrator

I believe that I have found a bug that is incorrectly causing incoming emails to be rejected with a "550 No Such User Here" (in reply to RCPT TO command)".

Here is the scenario...

Let's say there there is a website called "" on a cPanel, but the company uses an external mail server (not cPanel). So the cPanel only contains the website. There are no email accounts and the Email Routing is set to REMOTE.

If an email user from (which is a remote email server) sends an email to an address, that happens to be hosted on the same cPanel server as the "" website, but in a completely unrelated cPanel account, then that email will be rejected with the "550 No Such User Here" error. The incoming email is being checked for an email user in the cPanel account of "" on the same server cPanel server and not on the remote email server from which the email was sent.

This can be checked by creating a dummy email account in the name of the sending user in the website only cPanel account of ""; after which, incoming emails from the remote server with that same email address will then be accepted, although incoming emails from other aliases will be rejected unless fake email accounts are also set up for those aliases.

Whilst this might seem like a workaround, it is not practical to maintain dozens of ghost duplicate email accounts on the "" cPanel account, just because of a bug in the way cPanel is checking for email users.

Can this be corrected please?

Many thanks,



Jurassic Moderator
Staff member
Oct 19, 2014
cPanel Access Level
Root Administrator
Hey there! I wasn't able to reproduce this behavior on my end in a testing environment as I could send mail email normally without getting the 550 error.

Since you have a way to reproduce this, could you create a ticket with our support team so we can check this directly on an effected server?