From Postmaster Email Bouncing

Rick Cooper rcooper at
Sat Jun 9 18:16:38 IST 2012

I still haven't figured out of the error is coming from your internal server
or an external server. I haven't even considered sendmail for years but I am
sure there is a way for you to set a specific sub domain as an internal
domain so sendmail doesn't try to route the mail externally. I am assuming
you are not trying to send mail to the world from a server that has no world
routeable IP information, that would be very bad. If you are sending from an
internal server to a server that delivers to the outside and that server is
the one complaining such as 
user -> -> -> the world
what exactly is your structure internal->external->world or internal->world?
If it's the second then alias the internal to the external or add the
external as the MX for the internal and make sure the external knows it is
handling inbound for the
internal domain and it knows how to route them back to the internal server.
There is no reason to place the internal servers on a public IP but there
has to be a route for the mails to get where they are going if they send to
the world.,
if not configure your local sendmail to accept as local (
look at your sendmail local domains list where localhost and/or
localhost.localdomain are listed)


From: mailscanner-bounces at
[mailto:mailscanner-bounces at] On Behalf Of Kay Irmer
Sent: Friday, June 08, 2012 1:04 PM
To: MailScanner discussion
Subject: Re: From Postmaster Email Bouncing

The external IP of an international Mailserver must have an DNS resolution
and from my point of view also an valid Mx entry.
A reverse DNS should also be given.
For internal Subdomains masquerading to the main domain could also incr

Am 07.06.2012 um 19:02 schrieb Al Cooper <cooper at>:

Hi All,


A few weeks ago my server's emails sent from the postmaster user started to
bounce with the following error message: 


The following addresses had permanent fatal errors ----- <user>

    (reason: 553 5.1.8 <root at>... Domain of sender address
root at does not exist)

    (expanded from: <root at>)


It appears that my email is being blocked because there are not DNS records
for the sub-domain


If this is correct how do I change the postmaster sender address from to


Or is there a better solution?


Thanks for your help,



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