Build Postal SMTP Server & Send Bulk Emails Step by Step on Ubuntu 22.04

Postal-smtp-server

Building a Postal SMTP server to send bulk emails is a good choice for email marketers. Postal is very powerful and backed by a large community of developers. It is an open-source mail server script written in JavaScript and Ruby. It can be used to build in-house SMTP servers just like Mailgun, Sendgrid, Mailchimp, etc.

Postal installation is not very straightforward. The process is fairly complex. It’s because Postal needs several packages to be installed beforehand, it can be used. I have tried to make it as simple as possible.

Requirement for Postal SMTP server

  • A domain name from Namecheap or Namesilo
  • A VPS or cloud with a minimum of 4 GB RAM and 2 vCPU
  • Operating System: Ubuntu 22.04 or Ubuntu 20.04

I am using Contabo for the purpose of demonstration.

Initial Setup

In order to start with installation, you will need to connect to the server. If you are on you have to get an SSH client for this purpose. One such SSH client is Putty. But if you are on Linux or Mac, just open the terminal and type ssh@xx.x.x.xxx where xx.x.x.xxx is your server IP address.

First of all switch to root user

sudo -i

After that update and upgrade your Ubuntu

apt update -y
apt upgrade -y

Next set up the hostname. Replace “example.com” with your domain name.

hostnamectl set-hostname mail.example.com

Updating DNS records

Login to the domain registrar and create A record for mail.example.com

Now let’s begin with the installation.

Note: This is a new installation guide. If you are looking for an old installation guide scroll down.

Installing Docker and Docker-Compose

Recently postal team switched to docker mode to make installation easier for the end-users. Therefore we need to install Docker and Docker-Compose first. I already have discussed what is docker, docker-compose & installation steps in detail. Feel free to read the article to have a clear understanding of docker.

Installing Docker

First of all, set a few packages to set up the Docker repository

sudo apt-get install ca-certificates curl gnupg lsb-release

Next, add Docker’s official GPG key.

sudo mkdir -m 0755 -p /etc/apt/keyrings
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /etc/apt/keyrings/docker.gpg

Now, you can install the Docker repository using the following commands

echo \
  "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.gpg] https://download.docker.com/linux/ubuntu \
  $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null

Next update the system software

sudo apt-get update -y

Finally, run the following command to install Docker Engine and containerd.

sudo apt-get install docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin

Installing Docker-Compose

First of all download the current stable release of Docker Compose:

curl -SL https://github.com/docker/compose/releases/download/v2.16.0/docker-compose-linux-x86_64 -o /usr/local/bin/docker-compose

Next, update the permission to binary

sudo chmod +x /usr/local/bin/docker-compose

Also, create a symlink as well

sudo ln -s /usr/local/bin/docker-compose /usr/bin/docker-compose

Finally, test the docker-compose installation

docker compose version

You will see the docker-compose version. If you see anything else this means something has gone wrong.

Installing Additional Prerequisites for Postal SMTP

After installation of Docker and Docker-compose, you need to install a few other packages like Git, MariaDB, RabbitMQ, etc.

So, let’s install them one by one.

First, install git and git curl

apt install git -y
apt install git curl jq

Next clone the postal helper repository

git clone https://postalserver.io/start/install /opt/postal/install
sudo ln -s /opt/postal/install/bin/postal /usr/bin/postal

Installing MariaDB

Now, you can install MariaDB in the docker container

docker run -d \
   --name postal-mariadb \
   -p 127.0.0.1:3306:3306 \
   --restart always \
   -e MARIADB_DATABASE=postal \
   -e MARIADB_ROOT_PASSWORD=postalpassword \
   mariadb

Installing RabbitMQ

RabbitMQ is necessary to process messages and distribute the loads

To install it, run the following commands

docker run -d \
   --name postal-rabbitmq \
   -p 127.0.0.1:5672:5672 \
   --restart always \
   -e RABBITMQ_DEFAULT_USER=postal \
   -e RABBITMQ_DEFAULT_PASS=password \
   -e RABBITMQ_DEFAULT_VHOST=postalvhost \
   rabbitmq:3.8

Now we have installed all the prerequisite packages, it’s time to install Postal

Installing Postal

The postal repository, you installed earlier, is capable of generating some configuration files to use

Run the following command. 

postal bootstrap mail.example.com

The above command generates 3 files. Out of which postal.yml is of our interest.

You need to edit the postal.yml and make changes. But before that install an editor. I suggest installing nano.

apt install nano -y

Now to edit postal.yml run the following command

nano /opt/postal/config/postal.yml

You will see output something like this

  # The host that the management interface will be available on
  host: mail.example.com
  # The protocol that requests to the management interface should happen on
  protocol: https

web_server:
  # Specify configuration for the Postal web server
  bind_address: 172.105.33.83
  port: 5000

smtp_server:
  # Specify configuration to the Postal SMTP server
  port: 25

logging:
  # Specify options for the logging
  stdout: true

main_db:
  # Specify the connection details for your MySQL database
  host: 127.0.0.1
  username: root
  password: postalpassword
  database: postal

message_db:
  # Specify the connection details for your MySQL server that will be house the
  # message databases for mail servers.
  host: 127.0.0.1
  username: root
  password: postalpassword
  prefix: postal

rabbitmq:
  # Specify connection details for your RabbitMQ server
  host: 127.0.0.1
  username: postal
  password: password
  vhost: postalvhost

dns:
  # Specify the DNS records that you have configured. Refer to the documentation at
  # https://github.com/atech/postal/wiki/Domains-&-DNS-Configuration for further
  # information about these.
  mx_records:
    - mail.example.com
  smtp_server_hostname: mail.example.com
  spf_include: spf.mail.example.com
  return_path: rp.mail.example.com
  route_domain: routes.mail.example.com
  track_domain: track.mail.example.com

smtp:
  # Specify an SMTP server that can be used to send messages from the Postal management
  # system to users. You can configure this to use a Postal mail server once the
  # your installation has been set up.
  host: 127.0.0.1
  port: 2525
  username: # Complete when Postal is running and you can
  password: # generate the credentials within the interface.
  from_name: Postal
  from_address: postal@example.com

rails:
  # This is generated automatically by the config initialization. It should be a random
  # string unique to your installation.
  secret_key: b73a7e04571431c601d19a7688418eb395d059c1ada525dcfd337e978236be759e278367fb7c6773be625265d3d235ee98b4f8405957e4bbd1c4001f367442bf531843f690a1918626179bf297e31d5cd268c2f33339afd19b17ce901a3832bb9a8107f04bf1b702a4da16096141ed5c46cee3f739d3adabf89fa3cfd91f00cf

Cross-check your config file and then save and close the file with CTRL + X.

Initializing Database

Initializing Database is super easy, just execute the following command and you will see database tables were getting created in the output.

postal initialize

After that, it’s time to build postal

postal make-user

You will be asked for the email id, name, and password of the admin user. Type the answer and then go to the next step.

Starting & Running Postal

Starting and running postal is also super easy. Just run the following command.

postal start

You can check the status of postal

postal status

Installing Caddy

This is a new feature added by the Postal team to install SSL automatically.

docker run -d \
   --name postal-caddy \
   --restart always \
   --network host \
   -v /opt/postal/config/Caddyfile:/etc/caddy/Caddyfile \
   -v /opt/postal/caddy-data:/data \
   caddy

Now you can go to http://mail.yourdomain.com:5000 and log in using admin credentials. You will see the admin page something like this.

Postal-login-screen

In, the next article we will learn to create an organization, domain management, SMTP creation, etc.

Conclusion

Installing Postal is no longer a complex procedure. Since postal is open source and freeware, it would be a good start.

/77 Comments/by
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77 replies
      • Clement Godswill
        Clement Godswill says:

        Thanks for your reply. I bought several ips from contabo. I have followed your video and install postal successfuly. I have tried to Build a new mail server in postal, after adding a server name, I click on the build server button, it was just loading and loading without building any server. I can give you my postal login details, so you can see that my postal cannot build mail server

        Reply
          • Partha
            Partha says:

            Hi Sir
            I have the same error where I install postal also create organization successfully where i try to build a mail server just loading and loading. i have already check yml config file but don’t get any error but in postal status, i receive the below status msg, Please help

            postal_cron_1 /docker-entrypoint.sh post … Up
            postal_requeuer_1 /docker-entrypoint.sh post … Up
            postal_smtp_1 /docker-entrypoint.sh post … Exit 1
            postal_web_1 /docker-entrypoint.sh post … Up
            postal_worker_1 /docker-entrypoint.sh post … Up

  3. Jozef
    Jozef says:

    Why do you think i got this error?sudo apt-get install ruby2.3 ruby2.3-dev build-essential -y
    Reading package lists… Done
    Building dependency tree
    Reading state information… Done
    Package ruby2.3 is not available, but is referred to by another package.
    This may mean that the package is missing, has been obsoleted, or
    is only available from another source

    Package ruby2.3-dev is not available, but is referred to by another package.
    This may mean that the package is missing, has been obsoleted, or
    is only available from another source

    E: Package ‘ruby2.3’ has no installation candidate
    E: Package ‘ruby2.3-dev’ has no installation candidate

    Reply
  4. Jozef
    Jozef says:

    I got this error again when using this commend:
    sudo gem install nokogiri -v ‘1.7.2’
    Building native extensions. This could take a while…
    ERROR: Error installing nokogiri:
    ERROR: Failed to build gem native extension.

    current directory: /var/lib/gems/2.7.0/gems/nokogiri-1.7.2/ext/nokogiri
    /usr/bin/ruby2.7 -I /usr/lib/ruby/2.7.0 -r ./siteconf20210424-238639-mr7f7o.rb extconf.rb
    checking if the C compiler accepts … yes
    Building nokogiri using packaged libraries.
    Using mini_portile version 2.1.0

    Reply
  5. David
    David says:

    After that, install all the required dependencies with the following command:

    1. postal bundle /opt/postal/vendor/bundle

    “Could not find mail-2.7.2.edge in any of the sources”

    Please help me

    Reply
  6. Sandi
    Sandi says:

    Hi, thank you for your tutorials.

    I successfully install and use postal to send email from mautic via smtp (mautic on separated vps).

    But there is one problem left, i already use 8gb ram vps and the sending speed only around 50 emails/minute.

    I already increase the postal worker and do some mysql tuning that I found on postal github.

    Is there anything I could do to fix this? At least i need 500 emails/minute rate. I see on github there is a person who could send 300 emails/min with 4gb vps. So in my opinion I could get better performance.

    Before this I am using amazon ses via smtp with same mautic and there is no problem with sending speed rate.

    Thank you.

    Reply
  7. Ravi
    Ravi says:

    postal make-user gives this error, how to solve this pl.

    1: from /opt/postal/vendor/bundle/ruby/2.6.0/gems/mysql2-0.5.3/lib/mysql2/client.rb:90:in `initialize’
    /opt/postal/vendor/bundle/ruby/2.6.0/gems/mysql2-0.5.3/lib/mysql2/client.rb:90:in `connect’: Access denied for user ‘postal’@’localhost’ (using password: YES) (Mysql2::Error::ConnectionError)

    Reply
  8. Truong
    Truong says:

    I really love your article. Very nice!
    I have a question:
    I can only access my Postal server by using ‘http//:mail.mydomain.com:5000’ instead of the correct way is ‘https://mail.mydomain.com’ as your guide.
    Kindly help me with how to fix it?
    Thanks a lot!

    Reply
  9. moises
    moises says:

    Hi, i have one error, when i run postal initialize i got this error:
    Access denied for user ‘root’@’172.xx.xx.xx’ (using password: YES)
    Couldn’t create ‘postal’ database. Please check your configuration.

    Any idea how to solve this? iim using ubuntu 18.04

    Thanks

    Reply
  10. Francisco Ubieto
    Francisco Ubieto says:

    Hi Dhiraj,
    Thank you or the tutorials, I’ve followed it but run into trouble installing MariaDB

    Can’t connect to MySQL server on ‘127.0.0.1’ (115)
    Couldn’t create ‘postal’ database. Please check your configuration.
    rake aborted!
    and
    ERROR 1045 (28000): Access denied for user ‘root’@’localhost’ (using password: YES)

    I’ve tried uninstalling and installing, resetting the server, changing from ubuntu 18.04 to 20.0, using the old method and the new with docker…
    so far nothing works and my frustration is at an all-time high !!!

    the worst part is that I had the old version of Postal working but decided to update.
    I sent a private email, I hope you can help.
    Thanks.

    Reply
  12. Roy Colboure
    Roy Colboure says:

    Access denied for user ‘root’@’172.17.0.1’ (using password: YES)
    Couldn’t create ‘postal’ database. Please check your configuration.
    rake aborted!
    Mysql2::Error::ConnectionError: Access denied for user ‘root’@’172.17.0.1’ (using password: YES)

    pls i tried to do postal initialize, i keep getting this error every time, pls can you help me resolve it. Thanks

    Reply
  13. Roy Colboure
    Roy Colboure says:

    Access denied for user ‘root’@’172.17.0.1’ (using password: YES)
    Couldn’t create ‘postal’ database. Please check your configuration.
    rake aborted!
    Mysql2::Error::ConnectionError: Access denied for user ‘root’@’172.17.0.1’ (using password: YES)

    Hey Guru,
    i got this error message while trying to do postal initialize, please how can you help me solve it.
    Thanks

    Reply
  15. Iswor Lal Shrestha
    Iswor Lal Shrestha says:

    Hello, I am trying to install SMTP server as per your guideline. But I was stuck in install rabbitmq server. Can you please guide me on this section. Every time I am getting error for this step. Error: The repository is not signed.
    Looking forward to hearing from you.

    Thanks

    Reply
  16. Iswor Lal Shrestha
    Iswor Lal Shrestha says:

    postal_smtp_1 and postal_worker_1 always stop as soon as I start it. I install the postal v2. postal_web_1 is now running and hope it will run all the time. What could be the solution? Looking forward to hearing from you.

    Thanks

    Reply
  17. Iswor Lal Shrestha
    Iswor Lal Shrestha says:

    When I checked the postal logs, I got the error message as below:

    bundler: failed to load command: puma (/usr/local/bundle/bin/puma)
    Errno::EADDRNOTAVAIL: Cannot assign requested address – bind(2) for “172.105.33.83” port 5000

    How the above error can be solved?

    Looking forward to hearing from you.
    Thanks

    Reply
  18. CSCforMe
    CSCforMe says:

    Hi,
    I would like to install Mautic 4 and Postal on the same VPS. Any install guides to point me in the right direction?

    Reply
  19. greg
    greg says:

    Hello,

    thank you so much for the value of your content.

    I have been following the process and got stuck at the part where I need to bootstrap to mail.yourdomain.com.

    Putty tells me ” can’t connect to mail.mydomain.com ”

    Any idea where this comes from ? i though it was DNS pointing wrong but everything seems to be fine.

    I would appreciate if you could help figuring out where the problem comes from.

    Reply
  21. zeeshan
    zeeshan says:

    Hello,
    Getting below error when running postal initialize command.
    root@postal:~# postal initialize
    Pulling web … done
    Pulling smtp … done
    Pulling worker … done
    Pulling cron … done
    Pulling requeuer … done
    Creating postal_runner_run … done
    Initializing database
    No secret key was specified in the Postal config file. Using one for just this session
    Access denied for user ‘postal’@’172.17.0.1’ (using password: NO)
    Couldn’t create ‘postal’ database. Please check your configuration.
    rake aborted!
    Mysql2::Error::ConnectionError: Access denied for user ‘postal’@’172.17.0.1′ (using password: NO)
    /usr/local/bundle/gems/mysql2-0.5.3/lib/mysql2/client.rb:90:in `connect’
    /usr/local/bundle/gems/mysql2-0.5.3/lib/mysql2/client.rb:90:in `initialize’
    /usr/local/bundle/gems/activerecord-5.2.6/lib/active_record/connection_adapters/mysql2_adapter.rb:22:in `new’
    /usr/local/bundle/gems/activerecord-5.2.6/lib/active_record/connection_adapters/mysql2_adapter.rb:22:in `mysql2_connection’
    /usr/local/bundle/gems/activerecord-5.2.6/lib/active_record/connection_adapters/abstract/connection_pool.rb:830:in `new_connection’
    /usr/local/bundle/gems/activerecord-5.2.6/lib/active_record/connection_adapters/abstract/connection_pool.rb:874:in `checkout_new_connection’
    /usr/local/bundle/gems/activerecord-5.2.6/lib/active_record/connection_adapters/abstract/connection_pool.rb:853:in `try_to_checkout_new_connection’
    /usr/local/bundle/gems/activerecord-5.2.6/lib/active_record/connection_adapters/abstract/connection_pool.rb:814:in `acquire_connection’
    /usr/local/bundle/gems/activerecord-5.2.6/lib/active_record/connection_adapters/abstract/connection_pool.rb:538:in `checkout’
    /usr/local/bundle/gems/activerecord-5.2.6/lib/active_record/connection_adapters/abstract/connection_pool.rb:382:in `connection’
    /usr/local/bundle/gems/activerecord-5.2.6/lib/active_record/connection_adapters/abstract/connection_pool.rb:1033:in `retrieve_connection’
    /usr/local/bundle/gems/activerecord-5.2.6/lib/active_record/connection_handling.rb:118:in `retrieve_connection’
    /usr/local/bundle/gems/activerecord-5.2.6/lib/active_record/connection_handling.rb:90:in `connection’
    /usr/local/bundle/gems/activerecord-5.2.6/lib/active_record/tasks/mysql_database_tasks.rb:6:in `connection’
    /usr/local/bundle/gems/activerecord-5.2.6/lib/active_record/tasks/mysql_database_tasks.rb:14:in `create’
    /usr/local/bundle/gems/activerecord-5.2.6/lib/active_record/tasks/database_tasks.rb:119:in `create’
    /usr/local/bundle/gems/activerecord-5.2.6/lib/active_record/tasks/database_tasks.rb:139:in `block in create_current’
    /usr/local/bundle/gems/activerecord-5.2.6/lib/active_record/tasks/database_tasks.rb:316:in `block in each_current_configuration’
    /usr/local/bundle/gems/activerecord-5.2.6/lib/active_record/tasks/database_tasks.rb:313:in `each’
    /usr/local/bundle/gems/activerecord-5.2.6/lib/active_record/tasks/database_tasks.rb:313:in `each_current_configuration’
    /usr/local/bundle/gems/activerecord-5.2.6/lib/active_record/tasks/database_tasks.rb:138:in `create_current’
    /usr/local/bundle/gems/activerecord-5.2.6/lib/active_record/railties/databases.rake:29:in `block (2 levels) in ‘
    /opt/postal/app/bin/bundle:3:in `load’
    /opt/postal/app/bin/bundle:3:in `’
    Tasks: TOP => db:create
    (See full trace by running task with –trace)
    ERROR: 1
    can anyone help

    Reply
  24. Gregory
    Gregory says:

    I configured the SMTP using Postal.
    When I sent a test the email the email(s) stays in the queue and it gave me this error.:

    SMTP send error
    Failure sending mail.
    Unable to read data from the transport connection: The connection was closed.

    How do I remedy?

    Reply
  25. Mourad Baaqqa
    Mourad Baaqqa says:

    Hi,
    Can you please let me know if there is an advantage of getting a server with multipe IP addresses ?
    Can a single server use different domains for each of these IP addresses ?
    This could help instead of installing multiple servers

    Thanks in advance

    Reply
      • Mourad Baaqqa
        Mourad Baaqqa says:

        thanks very much for your feedback.
        The question is, Can Postal handle this, like use many IP addresses and many domains and rotate IP and Domains so that it will reduce the risk of being blacklisted?
        Thanks again

        Reply
  27. Indra Kumar
    Indra Kumar says:

    Using docker method, after using mariadb and rabbitmq, im getting an error of “invalid reference format”.

    Im using putty v0.77(64bit), digitalocean ubuntu 20.04

    pls help

    Reply
  28. John
    John says:

    I tried and i successfully did everything with digital ocean. But when trying to send message i keep getting soft fail and it won’t send out. Is it the vps or what do you think is the problem. Thank you

    Reply
  29. John
    John says:

    I tried and i successfully did everything with digital ocean. But when trying to send message i keep getting soft fail and it won’t send out. Is it the vps or what do you think is the problem.

    Reply
  30. Brian
    Brian says:

    This site can’t be reachedmail.supportme365.com refused to connect.
    Try:

    Checking the connection
    Checking the proxy and the firewall
    ERR_CONNECTION_REFUSED

    I receive this message when I try to log in to postal though the status of postal is correct on the server.
    please help me out

    Reply
  31. Brian
    Brian says:

    root@mail:~# postal start
    Starting postal_web_1 … done
    Starting postal_smtp_1 … done
    Starting postal_worker_1 … done
    Starting postal_cron_1 … done
    Starting postal_requeuer_1 … done
    root@mail:~# postal status
    Name Command State Ports
    ——————————————————————
    postal_cron_1 /docker-entrypoint.sh post … Up
    postal_requeuer_1 /docker-entrypoint.sh post … Up
    postal_smtp_1 /docker-entrypoint.sh post … Up
    postal_web_1 /docker-entrypoint.sh post … Up
    postal_worker_1 /docker-entrypoint.sh post … Up
    root@mail:~#

    Reply
  32. gouarv
    gouarv says:

    where to set ip for ip pools. have i to do some changes in postal.conf for ip rotation and what to write hostname for external ip.

    Please resolve my problem as soon as possible.

    Reply
  33. stephanie
    stephanie says:

    please i keep getting this error when i try to login mail.loginmall.live:5000 . what can i do to fix this please

    This site can’t be reachedmail.loginmall.live refused to connect.
    Try:

    Checking the connection
    Checking the proxy and the firewall
    ERR_CONNECTION_REFUSED

    Reply
  34. Raj
    Raj says:

    I am getting this message when i am logging on to my mail server – “We’re sorry, but something went wrong.
    If you are the application owner check the logs for more information.”

    Reply
  35. Pavan
    Pavan says:

    First of all, thank you the detailed tutorial.
    I have successfully setup postal and generated my credentials.

    I’m running to issues when I try to integrate postal on mailwizz or mautic.
    On Mailwizz,
    the error is “Cannot send the confirmation email using the data you provided.
    ×
    Here is a transcript of the error message:
    Couldn’t send message to API”
    I even tried the SMTP credentials to add but for some reason I’m unable to validate my delivery server.

    I tested the credentials, tested emails everything works flawlessly but I’m not sure why not the integration.

    Please advise.

    Thank you

    Reply
    • Dhiraj Rahul
      Dhiraj Rahul says:

      I think you are using incorrect username of postal. Go to credentials > Read more about sending outgoing e-mails
      There you will get the username.

      Alternatively, you can check your smtp credentials at gmass.co before putting into Mailwizz

      Thanks

      Reply

Trackbacks & Pingbacks

  1. Simplest Way to Configure Postal & Create SMTP + Install SSL - inGuide | Digital Marketing, Online Business & WordPress says:
    March 27, 2021 at 9:21 am

    […] the article Install Postal SMTP server on Ubuntu 18.04, I already have discussed steps to install Postal Successfully. Now in this article, I will tell […]

    Reply

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