Posts Tagged ‘relay mail’

How to configure Exim to relay mail to remote SMTP server on Debian and Ubuntu

Wednesday, August 24th, 2011

I’m required to do some mail relaying on a Debian Linux host which should use a remote mail server to relay its mails.
Until so far I’ve had not much experience with exim as I prefer using qmail, whever a mail server is needed. However since now only a relaying was necessery and exim is the default installed MTA on Debian, I’ve decided to use exim to take care of the SMTP mail relaying.
After a bit of reading it happened configuring exim to relay via remote SMTP server is more than easy!

All I had to do is run the command:

debian-relay:~# dpkg-reconfigure exim4-config

Next in the Ncruses interface to appear:

Debian Exim relay smtp config screenshot

I had to choose the option:

mail sent by smarthost; no local mail

Next a dialog appears asking for:
System mail name:
Therein it’s necessery to type in the hostname of the remote SMTP to be used for mail relay.
Next dialog asks for:
IP-addresses to listen on for incoming SMTP connections:
and I left it with however if exim is supposed to be visible from external network one might decide to put in real IP address there.

Pressing OK leads to the next dialog:
 Other destinations for which mail is accepted: 
I decided to leave this blank as I don’t want to accept mail for any destinations.
Next pane reads:
Visible domain name for local users:
I’ve typed inside my smtp relay server e.g.:

Further comes:
IP address or host name of the outgoing smarthost:
There once again I typed my mail relay host

The next config screen is:
Keep number of DNS-queries minimal (Dial-on-Demand)?
On any modern Linux host the default answer of No is fine.
Following prompt asked if I want to:
Split configuration into small files?
I’ve decided not to tamper with it and choosed No
Afterwards mail relaying works like a charm thx God 😉

How to configure mail server forwarding on Postfix – Email forwarding from one Postfix SMTP to another

Friday, March 1st, 2013

I needed to configure mail forwarding from one Postfix mail server with a correct MX and PTR record to another one for a reason the second mail server has filtered port 25, because of ISP policy. As it is recommended in such situations, I've configured mail forwarding from postfix host1 to host2 to use (submission) port number 587 which general purpose is for exactly situations like this. Mail forwarding is done via a simple /etc/postfix/, /usr/local/etc/postfix/ (depending where Postfix is installed).

Thus as my postfix configs are in /etc/postfix, I edited /etc/postfix/ on forwarding Postfix mail server, where mail comes in (host1) and added line:

relayhost = []:587

Where is IP address of host2

To load settings I had to do the usual postfix restart

postfix# /etc/rc.d/postfix restart

postfix/postfix-script: stopping the Postfix mail system
postfix/postfix-script: starting the Postfix mail system

On host2 – to which mail is forwarded, I had to add access for host1 to relay mail  in /etc/postfix/ had to include:

mynetworks =

and is IP of host1

One note to make is if mynetworks is not defined to host of host1 mail server, you will get in /var/log/maillog error:

Relay access denied (in reply to RCPT TO command))

Here is paste chunk from /var/log/maillog

Mar  1 08:57:01 host1 postfix/smtp[95236]: 88C8B11F911:
                    to=<>, relay=[]:587, delay=0.54,
                    delays=0.01/0/0.44/0.09, dsn=5.7.1, status=bounced (host[] said: 554 5.7.1
                    <>: Relay access denied (in reply to RCPT TO command))