Postfix is a popular open-source Mail Transfer Agent (MTA) that can be used to route and deliver email on a Linux system. It is estimated that around 25% of public mail servers on the internet run Postfix.
In this guide, we’ll teach you how to get up and running quickly with Postfix on an Ubuntu 16.04 server.
In order to follow this guide, you should have access to a non-root user with sudo
privileges. You can follow our Ubuntu 16.04 initial server setup guide to create the necessary user.
In order to properly configure Postfix, you will need a Fully Qualified Domain Name pointed at your Ubuntu 16.04 server. You can find help on setting up your domain name with DigitalOcean by following this guide. If you plan on accepting mail, you will need to make sure you have an MX record pointing to your mail server as well.
For the purposes of this tutorial, we will assume that you are configuring a host that has the FQDN of mail.example.com
.
Postfix is included in Ubuntu’s default repositories, so installation is incredibly simple.
To begin, update your local apt
package cache and then install the software. We will be passing in the DEBIAN_PRIORITY=low
environmental variable into our installation command in order to answer some additional prompts:
- sudo apt-get update
- sudo DEBIAN_PRIORITY=low apt-get install postfix
Use the following information to fill in your prompts correctly for your environment:
mail.example.com
, but we probably want to set the system mail name to example.com
so that given the username user1
, Postfix will use the address user1@example.com
.root@
and postmaster@
. Use your primary account for this. In our case, sammy.To be explicit, these are the settings we’ll use for this guide:
If you need to ever return to re-adjust these settings, you can do so by typing:
- sudo dpkg-reconfigure postfix
The prompts will be pre-populated with your previous responses.
When you are finished, we can now do a bit more configuration to set up our system how we’d like it.
Next, we can adjust some settings that the package did not prompt us for.
To begin, we can set the mailbox. We will use the Maildir format, which separates messages into individual files that are then moved between directories based on user action. The other option is the mbox format (which we won’t cover here) which stores all messages within a single file.
We will set the home_mailbox
variable to Maildir/
which will create a directory structure under that name within the user’s home directory. The postconf
command can be used to query or set configuration settings. Configure home_mailbox
by typing:
- sudo postconf -e 'home_mailbox= Maildir/'
Next, we can set the location of the virtual_alias_maps
table. This table maps arbitrary email accounts to Linux system accounts. We will create this table at /etc/postfix/virtual
. Again, we can use the postconf
command:
- sudo postconf -e 'virtual_alias_maps= hash:/etc/postfix/virtual'
Next, we can set up the virtual maps file. Open the file in your text editor:
- sudo nano /etc/postfix/virtual
The virtual alias map table uses a very simple format. On the left, you can list any addresses that you wish to accept email for. Afterwards, separated by whitespace, enter the Linux user you’d like that mail delivered to.
For example, if you would like to accept email at contact@example.com
and admin@example.com
and would like to have those emails delivered to the sammy
Linux user, you could set up your file like this:
contact@example.com sammy
admin@example.com sammy
After you’ve mapped all of the addresses to the appropriate server accounts, save and close the file.
We can apply the mapping by typing:
- sudo postmap /etc/postfix/virtual
Restart the Postfix process to be sure that all of our changes have been applied:
- sudo systemctl restart postfix
If you are running the UFW firewall, as configured in the initial server setup guide, we’ll have to allow an exception for Postfix.
You can allow connections to the service by typing:
- sudo ufw allow Postfix
The Postfix server component is installed and ready. Next, we will set up a client that can handle the mail that Postfix will process.
Before we install a client, we should make sure our MAIL
environmental variable is set correctly. The client will inspect this variable to figure out where to look for user’s mail.
In order for the variable to be set regardless of how you access your account (through ssh
, su
, su -
, sudo
, etc.) we need to set the variable in a few different locations. We’ll add it to /etc/bash.bashrc
and a file within /etc/profile.d
to make sure each user has this configured.
To add the variable to these files, type:
- echo 'export MAIL=~/Maildir' | sudo tee -a /etc/bash.bashrc | sudo tee -a /etc/profile.d/mail.sh
To read the variable into your current session, you can source the /etc/profile.d/mail.sh
file:
- source /etc/profile.d/mail.sh
In order to interact with the mail being delivered, we will install the s-nail
package. This is a variant of the BSD xmail
client, which is feature-rich, can handle the Maildir format correctly, and is mostly backwards compatible. The GNU version of mail
has some frustrating limitations, such as always saving read mail to the mbox format regardless of the source format.
To install the s-nail
package, type:
- sudo apt-get install s-nail
We should adjust a few settings. Open the /etc/s-nail.rc
file in your editor:
- sudo nano /etc/s-nail.rc
Towards the bottom of the file, add the following options:
. . .
set emptystart
set folder=Maildir
set record=+sent
This will allow the client to open even with an empty inbox. It will also set the Maildir
directory to the internal folder
variable and then use this to create a sent
mbox file within that, for storing sent mail.
Save and close the file when you are finished.
Now, we can test the client out.
The easiest way to create the Maildir structure within our home directory is to send ourselves an email. We can do this with the mail
command. Because the sent
file will only be available once the Maildir is created, we should disable writing to that for our initial email. We can do this by passing the -Snorecord
option.
Send the email by piping a string to the mail
command. Adjust the command to mark your Linux user as the recipient:
- echo 'init' | mail -s 'init' -Snorecord sammy
You should get the following response:
OutputCan't canonicalize "/home/sammy/Maildir"
This is normal and will only show during this first message. We can check to make sure the directory was created by looking for our ~/Maildir
directory:
- ls -R ~/Maildir
You should see the directory structure has been created and that a new message file is in the ~/Maildir/new
directory:
Output/home/sammy/Maildir/:
cur new tmp
/home/sammy/Maildir/cur:
/home/sammy/Maildir/new:
1463177269.Vfd01I40e4dM691221.mail.example.com
/home/sammy/Maildir/tmp:
It looks like our mail has been delivered.
Use the client to check your mail:
- mail
You should see your new message waiting:
Outputs-nail version v14.8.6. Type ? for help.
"/home/sammy/Maildir": 1 message 1 new
>N 1 sammy@example.com Wed Dec 31 19:00 14/369 init
Just hitting ENTER should display your message:
Output[-- Message 1 -- 14 lines, 369 bytes --]:
From sammy@example.com Wed Dec 31 19:00:00 1969
Date: Fri, 13 May 2016 18:07:49 -0400
To: sammy@example.com
Subject: init
Message-Id: <20160513220749.A278F228D9@mail.example.com>
From: sammy@example.com
init
You can get back to your message list by typing h:
- h
Outputs-nail version v14.8.6. Type ? for help.
"/home/sammy/Maildir": 1 message 1 new
>R 1 sammy@example.com Wed Dec 31 19:00 14/369 init
Since this message isn’t very useful, we can delete it with d:
- d
Quit to get back to the terminal by typing q:
- q
You can test sending mail by typing a message in a text editor:
- nano ~/test_message
Inside, enter some text you’d like to email:
Hello,
This is a test. Please confirm receipt!
Using the cat
command, we can pipe the message to the mail
process. This will send the message as your Linux user by default. You can adjust the “From” field with the -r
flag if you want to modify that value to something else:
- cat ~/test_message | mail -s 'Test email subject line' -r from_field_account user@email.com
The options above are:
-s
: The subject line of the email-r
: An optional change to the “From:” field of the email. By default, the Linux user you are logged in as will be used to populate this field. The -r
option allows you to override this.user@email.com
: The account to send the email to. Change this to be a valid account you have access to.You can view your sent messages within your mail
client. Start the interactive client again by typing:
- mail
Afterwards, view your sent messages by typing:
- file +sent
You can manage sent mail using the same commands you use for incoming mail.
You should now have Postfix configured on your Ubuntu 16.04 server. Managing email servers can be a tough task for beginning administrators, but with this configuration, you should have basic MTA email functionality to get you started.
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Two small typos:
I think the first part should be formatted as bold (I guess that is where the ** are coming from…)
I think this should be /etc/postfix/virtual
Very useful (The best explanation I’ve read here) and the only one who worked for me, maybe because the Ubuntu version, all tutorials are quite same but they are Ubuntu’s 14 or minus.
Can you add Courier/Dovecot setup please? Same, for Ubuntu 16.04
Thank you
Thanks for the guide Justin, however I’ve messed up somewhere at this step
It tells me there’s not such file or directory and I’ve tried to restart the console and now I cannot enter any commands just a blank line. Whatever I type in and press enter, it comes out 2 times.
Did You even check how the command prompts work?
to restart postfix You give this command line:
But it’s incorrect, an error is given:
To get the postfix restarted, You have to give this command line instead:
I got Relay access denied error… pls help…
Quick question: Is this what it needs to be done if one would like to operate simple contact forms from a droplet? The contact forms will be able to send e-mails. Or is there a simpler way around?
Quick question:
If my FQDN is not mail.example.com as in your above tutorial, but instead, my FQDN is just example.com what additional steps would be involved to continue following your tutorial above, and would it not be good practice to use my example.com domain for both email and web hosting or would that be ok? Sorry if this has been asked already, but I have already tried searching for answers. :(
Based on what I already understand, mail would be a sub-domain off of example.com correct? Or is that an entirely different domain altogether?
Hi,
Disregard my last message, as I have followed everything in this tutorial and from top to bottom it worked exactly as expected, my only question now is that I want to now setup thunderbird email client with my contact@domain.com email address, and check the mail, but I didn’t have to set a username or password throughout this tutorial, is there something I have missed or can you point me to the correct page to allow me to configure my email for ‘external use’ if that is the correct way to put it?
Sorry for the last message, just learning the ropes.
Thank you Brian
Thanks for this tutorial, it is very well written. It is all working on my server, sending and receiving emails, the problem I’m having is when I try to login via a email client it keeps telling me my username and password are incorrect, how can I fix this problem?
I followed this tutorial completely, but still my emails are not going to my email address.
Although emails are being saved to local Maildir directory under home folder.
Can you please help me sending emails to any email address from my server. I am using php to send emails and want to send emails to any email address which I specify in my files.
If there is any other tutorial to follow to do what I want?