I have two hosting accounts, personaldomain.com and companydomain.com. Both have User level cPanel. Whenever I try to send email from personaldomain.com to any email address on companydomain.com, I instantly receive a Mail Delivery System message saying:

Subject: **Mail delivery failed: returning message to sender**

A message that you send could not
be delivered to one or more of its
recipients. This is a permanent error.
The following address(es) failed:

[email protected]
  No Such User Here

This only happens from personaldomain.com to companydomain.com, and not the other way. I've tried each address, and looking at the headers, it doesn't seem to be leaving my mail server:

Received: from ns1.usm4.siteground.biz ([my-ip-address] helo=mymailserver1.usm4.siteground.biz)
         by se8.mailspamprotection.com with esmtps (TLSv1.2:DHE-RSA-AES256-SHA:256)
         (Exim 4.85)
         (envelope-from <[email protected]>)
         id 1aYcMc-0003NN-Qz
         for [email protected]; Wed, 24 Feb 2016 10:32:37 -0600
 Received: from localhost ([]:38882 helo=mymailserver.usm4.siteground.biz)
         by mymailserver1.usm4.siteground.biz with esmtpsa (TLSv1:DHE-RSA-AES256-SHA:256)
         (Exim 4.80.1)
         (envelope-from <[email protected]>)
         id 1aYcMc-0007Zf-Lg
         for [email protected]; Wed, 24 Feb 2016 11:32:34 -0500
 Received: from an-ip-address ([an-ip-address]) by mysubserver.sgcpanel.com
  (Horde Framework) with HTTP; Wed, 24 Feb 2016 16:32:34 +0000
  Date: Wed, 24 Feb 2016 16:32:34 +0000
 [more content headers and filters]
 X-SpamExperts-Outgoing-Class: ham
 X-SpamExperts-Outgoing-Evidence: Combined (0.29)
 X-Recommended-Action: accept

I also noticed that the returned emails have a time of 4:32am when my server is 11:32am EST (sending from Webmail Horde) and my local time is 10:32am (sending from Outlook or iPhone). I don't know if that affects the authentication.

I'm able to send to companydomain.com from any other email address. I'm able to send to any other domain from personaldomain.com.

How can I figure out the source of this error, so I can fix it?

  • Thought I should add that I've whitelisted both domains between each other.
    – AceOS
    Commented Feb 24, 2016 at 17:31

3 Answers 3


A 550 error code means that your SMTP server isn't able to deliver the sent email to the user because recipient mailbox does not exist. According to me if your hosting account is running on shared environment rather than dedicated then please contact your hosting service provider and say them to check your e-mail functionality. Might be your email functionality have disabled by them for any bla bla reason.

  • Thing is, it works for every other domain I've tried. It's only from one specific domain to another specific domain. It is a virtual server, but I control all the MX records and spam settings, just don't know where to find the error log.
    – AceOS
    Commented Feb 24, 2016 at 20:13
  • Can you you please paste some exim_mainlog. so i can assist you better.
    – mAfiA
    Commented Feb 25, 2016 at 17:44
  • 1
    It turns out it wasn't anything to do with the email system. I started working on another server-side project, and my personal server could not reach my work server through HTTP request, so I started digging, and apparently it's a DNS issue of some kind. I have both hosting companies working on it.
    – AceOS
    Commented Feb 26, 2016 at 23:56
  • You mean CASE CLOSED :D
    – mAfiA
    Commented Mar 1, 2016 at 4:23

This happens when u have both domain hosting configured under the same server. the issue happens from the receiver domain only if the hosting is configured in same server but email is configured in another/remote server. When u send a email it checks the local server for the same domain first for email address.

what you have to do is configure the route email to remote email server on the receiver hosting settings in the same server. this will resolve the issue.



  1. Email Routing in cPanel.


  1. Remote Mail Exchanger.

Email Routing

Note: Make sure your MX and other email DNS records are on your host first.

  • Although they didn't answer their own question, the OP has clarified the issue in a comment on another answer. Your answer may apply sometimes, but not in this case.
    – Steve
    Commented Mar 25, 2022 at 23:47

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