In order to test this configuration, you will need to set up a DNS server and configure a central mail server (here at 192.168.1.1) to receive mails.
Remove the sendmail package (sendmail is more complicated to configure):
# yum erase sendmail
Install the postfix package:
# yum install -y postfix
Activate the postfix service at boot:
# chkconfig postfix on
Start the postfix service:
# service postfix start
Let’s assume that your local server is called server.example.com on the 192.168.1.0/24 network and your smart host (outgoing mail gateway) is at 192.168.1.1.
Edit the /etc/postfix/main.cf file and change the following directives:
myhostname = server.example.com mydomain = example.com myorigin = $mydomain inet_interfaces = all mydestination = $myhostname, localhost.$mydomain, localhost mynetworks = 192.168.1.0/24, 127.0.0.0/8 relayhost = 192.168.1.1
Check the syntax:
# postfix check
Check the non-default configuration:
# postconf -n
Reload the postfix configuration:
# service postfix reload
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14 Comments on "SMTP: Configure a MTA to forward (relay) email through a smart host."
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Hi,
thank you so much for those tutos, but here i am a little bit confused.
what’s the hostname or ip address for central mail server?
what’s the hostname or ip address for the smart host?
and the main.cf file in which host are we supposed to edit it?
thank a lot
The IP address for the central mail server is 192.168.1.1 in the tutorial. Also, the central mail server and the smart host are the same server. The main.cf file to edit is the one on the machine that needs to send mails.
i got it. thank you
You’re welcome.
HI,
I have one question for you. if i want to block a client with 192.168.1.20 for example to send email how am i going to proceed?
thank you
Look at this page: http://www.linuxlasse.net/linux/howtos/Blacklist_and_Whitelist_with_Postfix
This should answer your question.
thank you so much
Hi,
I just stumbled upon this article when I searched postfix configuration file setups. I have a more general question here: do I have to have a private domain name and a private server name to be able to use your tutorial here? By the way, I don’t own a domain name and I don’t have a server at home. I can send email out through gmail relay only from command line, but not receive emails.
Thanks.
Mail reception goes with DNS and MX field configuration. So you need to own a domain name to be able to receive emails through Postfix or any other software.
Just to add something, you do not have to have a private domain nor a private server to be able to use the tutorial, if you send emails from the computer where the Postfix server is configured, and relay to your Gmail mailbox.
For example, this tutorial would work on your laptop if you were to install Postfix on it and configure relay to your Gmail account. You would be able to send emails from your PC to Gmail via Postfix. It is not clear on what exactly you want to achieve here, therefore more details would be helpful.
Just a thought, to read the emails, through gmail, is the setting correct through the encryption / 2 factor authentication. I imagine this can be difficult.
If you use Gmail, then Postfix works as a relay. Your mailbox is hosted on Gmail. When an email “comes back”, it goes to Gmail, not Postfix. To be able to retrieve incoming GMAIL messages you need a POP/IMAP client, but not Postfix.
You can configure all the above on your computer without having to purchase a single domain or to buy a server. However, if you don’t want Gmail but prefer to host your own email server, then yes, you need to have a domain and a place to run it. I hope this clarifies things.