I think "Auto Responder" is setup right for Email address
on server Boru

send Email to Email address

can read it with both Webmail in cPanel
and POP3 via Email client

BUT

"Auto Responder" throws Email back to you (sender) as
==>
subject: Mail delivery failed: returning message to sender

This message was created automatically by mail delivery software.

A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. The following address(es) failed
--------------------- 8< ------- snip ---------------------------------------------------
<==