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horrorshow 29th March 2013 10:14

ISPConfig - Mail() does not route to remote MX when to domain on local server
Originally posted this in the wrong forum. I think this may be an ISPConfig bug but wanted to make sure, or see if there's a simple way to resolve this.

Running Postfix/courier

Linux 2.6.32-042stab055.16 #1 SMP Fri Jun 8 19:22:28 MSD

CentOS release 6.3 (Final)

Added an entry in Advanced Mail Routing for the domain to googles SMTP ip address.

When I try to send an email using PHP's mail() function to any other email address, it works fine. When sending to an email address of a site on the local server, it tries to route it to localhost, where it doesn't find any email account because the mail account is on google apps remote mx:

Mar 28 15:01:31 vds1 postfix/smtpd[582]: NOQUEUE: reject: RCPT from localhost[]: 550 5.1.1 <>: Recipient address rejected: User unknown in relay recipient table; from=<> to=<> proto=ESMTP helo=<>

Mar 28 15:01:31 vds1 sendmail[652]: r2SC1UVX000652:, (48/48), delay=00:00:01, xdelay=00:00:00, mailer=relay, pri=30079, relay=[] [], dsn=5.1.1, stat=User unknown

The domain is added as a site, but not a mail domain. Do I have this configured wrong, or is something else wrong? This is causing a form to not properly deliver emails.


pititis 30th March 2013 00:16


User unknown in relay recipient table
You must define what will be relayed to google under Email->Relay Recipents. Just add the full email address there.


horrorshow 30th March 2013 00:44

Is it possible to add the entire domain or wildcard?

pititis 30th March 2013 00:48

Yes with but is very dangerous, you can become a backscatter source. Anyone can send you an email to a non existing address and the remote server will be send a bounce.

horrorshow 30th March 2013 22:54

I am curious about this. Since the MX is going to google apps, all emails should go there anyway, so how would this generate backscatter involving the local server settings? Wouldn't this only be a potential issue if the local server was compromised or the mail() script was easily abused?

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