Email Communication Between Domains


**For privacy reasons, I will not be using actual domain names in my question below.

I have a linode, hosting 7 domains using VestCP control panel. One domain on this linode is and it has been set with Google Apps mail servers.

The problem is that any mails sent from this domain or sent to this domain from any other domain hosted on this linode bounce back.

An example is that I sent an email to from and following is the error.

=== 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: Unrouteable address Reporting-MTA: dns;

Action: failed Final-Recipient: rfc822; Status: 5.0.0


On the other hand, I sent email from to and following is the error.


Address not found Your message wasn't delivered to because the address couldn't be found, or is unable to receive mail. The response from the remote server was: 550 Verification failed for Unrouteable address Sender verify failed

Kindly help

1 Reply

I want to preface this by saying that because I cannot see your domains nor your DNS configuration,I'm going to do my best to get you pointed in the right direction.

Because you're using VestaCP, I started researching on their forums. I want to start with this error message: Unrouteable address Reporting-MTA: dns;

A potential solution I found for this, other than making sure your mail ports are open, is making sure the hostname is properly set:

Unrouteable Address Error

Also, I found in a CPanel forum that this could be caused by an email filter or a cron job (where your filter settings are located is dependent on your mail server):

A message that you sent could not be delivered

As for the 550 Verification failed error you're receiving, there could be several reasons for this - but the issue is likely with the receiving address.

One cause is that the email address simply doesn't exist. However, I'm going to assume that is probably not the issue here.

Another of the causes could be misconfigured MX records. I recommend comparing yours with our guides, which I'll link here:

DNS Records - MX

Running a Mail Server - MX Records

Another potential fix for this I found in the VestaCP forums, and it's presented that this might be a permissions error:

SMTP Error 550


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