OWN SMTP Server Setup with Postal (Step by Step Guide)
In this Step by Step Guide, I will show you how to set up a Free SMTP server using Postal, the open source SMTP software, and connect it to your email marketing application to send Unlimited Emails*.
Also, you will find a video below Showing the setup if you feel something is unclear.
There are several methods to build SMTP servers, in this guide I will build the SMTP server using a free open source software called “Postal“.
Postal is a fully-featured open source mail delivery platform for incoming & outgoing e-mail and gives you all the tools and features needed to build a full mailing system for your business.
What is the SMTP Server?
I don’t like robotic definitions like Wikipedia, I love to make things simple. So…
Simply, SMTP is that thing that allows you to send emails over the internet.
SMTP stands for “Simple Mail Transfer Protocol”. It’s a Concept in Networking that you don’t have to worry about.
Just Know that SMTP is the technical thing that is responsible for delivering emails over the internet.
Let’s connect things, how this is related to email marketing?
I think it’s clear, but just in case, and As I explained in my Techincal Email Marketing guide, any Email marketing system consists of two parts:
The sender: (SMTP service) this is the technical part. It allows you to send emails over the internet.
The Management Application, where you can configure and manage your Email Lists, Marketing Campaigns, monitor and analyze results, manage your sending servers, and so on.
So we connect both together to get an Email Marketing System.
Email Marketing System
So now I think It’s SUPER clear, we are going to learn how to build the first part of any email marketing system which the SMTP server.
Need more details?
Maybe you are that person who loves to go deep in topics and understand everything in detail like me if you are that person, you can watch the following 3 minutes video to learn more about SMTP servers and how it works:
What do we mean by Sending Unlimited Emails?
When we say unlimited emails, this means that we can send unlimited emails from our server, there are no restrictions by companies or monthly plans to buy or so.
It’s your own server, u can send as much your server can handle in terms of resources. so when you have more (CPU and RAM), you can send more emails and so on.
Setup the SMTP Server, Let’s Start!
Ok, So Let’s start the real work! but before, you need to know what is required.
Requirements to Setup SMTP Server.
In order to Build and Setup an SMTP Server, you will mainly need two things:
A Domain name
VPS Server with port 25 opened.
1. Domain name
When you send emails, you will be sending from an email address like this one:
dileep.rajput7@gmail.com
So in my case, “H-educate.com” is the domain name that I use to send my emails. so simply it’s required to have a domain name to use when you send emails from your SMTP server.
Usually, it’s your website domain name, except if you are working with cold emails, then it’s better to get and use another domain in case it got blacklisted, to keep your main business domain safe.
So if you don’t have a domain yet, go and get one NOW! in order to continue the Setup.
How to get a domain? simply you buy one! and it costs around 10$ per year, so it’s not that big deal!
We have a lot of DOMAIN REGISTRATION PROVIDERS where you can get a domain from like:
Godaddy.
Namecheap.
freenom.
Enom.
Google Domain.
Here in the course, I will be using Godaddy to get my domain, but you can use any other service if you want, all work in the same way, and if you need any help, I will be here
You can watch this 3 minutes video to see how to get and buy a domain from Godaddy Domain Registrar if you are a beginner.
This video is part of my Top Rated Course On Udemy:
Got a Domain? Great! Let’s continue.
2. VPS Server with Port 25 opened.
The second thing you will need is a VPS server. a public server to install & Setup SMTP on.
What is a VPS server?
If you don’t know what is a VPS server, simply its a computer (a server) running in the cloud that you buy from a Web Hosting or Cloud Services company. And it’s publicly accessible with a Public IP.
A VPS can be used to host your websites with higher performance, can be used to run a machine 24/7 in the cloud to do any task you want.
Note: If you are interested in learning how to host your own websites on a VPS server, you can
Anyway, In our case, we will be using the VPS Server for Building an SMTP server.
Port 25 open??
I mentioned that the VPS must have port 25 opened, what does this mean?
I don’t want to bother your head within deal technical stuff but in short. Any network service or software uses a certain port to communicate over the internet or network. Examples:
Connecting remotely to another Windows Machine using RDP software works over port 3389.
SQL database systems like MYSQL on our computer works over port 3306.
Connecting to a Linux machine remotely to manage it with SSH, uses port 22.
When you surf the web and open websites, we use port 80. and so on.
By default, all servers and computers have a firewall running which blocks all ports except the ones you want. so In order to use a certain service, we need to open that port in the firewall.
What you have to know also, that ports can be blocked and opened in two ways, incoming and outgoing, the following diagram will make things clearer:
Inbound and Outbound Ports
I recommend you to watch my free course “Amazon EC2 for Digital Marketers” you will understand all these concepts in less than an hour.
So, in our case, we are building an SMTP server, and the SMTP software or protocol communicates over port 25. so we need to have port 25 opened.
So when you get a VPS server, just make sure that the company allows Port 25 and don't block it, because some companies do this to protect from spammers.
Port 25 is used to send emails
Here is a list of some companies that allows port 25 by default:
Host wind.
Contabo.
Interserver.
OVH.
Digital Ocean*
AWS (some accounts are blocked)
*Digital Ocean Sometimes block some accounts and restrict port 25, but in general they allow all ports.
Are there any other Companies?? yes, simply you can contact the support of any company you want and ask if they block any ports by default. if not, then perfect, you can go with it.
Feel free to use any VPS company you want, It’s up to you!
You can also sign up on DigitalOcean through the coupon link below to get free 100$ to test everything free.
Digital Ocean Coupon Link
So Choose your VPS company and let’s get one.
After you select your VPS company, just create a VPS Server with the following specifications:
Ubuntu 18 x64 as your operating system
You can start with 1 CPU/2 GB RAM (And resize later).
Got your VPS? Great! Let’s continue.
VPS Server basic configuration.
Now we have our new Ubuntu VPS server, Let’s prepare it for out Setup.
Connect to your server, using an SSH client like putty or bitvise.
First, check your hostname:
hostname -f
If you don’t see a form of ANYTING.YOURDOMAIN.COM, then you need to change the hostname using the following command:
sudo hostname host.domain.tld
Where the host is anything you want. so in my case, my sample domain for this tutorial is xmailing.me, the command will look like this:
sudo hostname postal.xmailing.me
Map your domain name.
Now we have our VPS server and we set its name. Go to your Domain Provider and map your Domain to your VPS server. simply open DNS management zone and add a new A record like this:
host: server points: YOUR SERVER IP.
Godaddy A record
*server is in my case, you can choose whatever you want for your server name.
Done? Let’s continue.
Setup Free SMTP Server
The VPS is ready, and we can start the installation process. So in order to setup SMTP Server on our VPS, we need to install an SMTP software.
Install Postal Free SMTP Software
We have several SMTP Software like PowerMTA, Postal, Exim, Postfix…
In this guide, we will be using Postal as our SMTP software (service). So Let’s start:
If you selected Contabo as your VPS provider, you will need to run the following command on your server before you start:
sudo apt-get install apt-transport-https
To Install Postal, simply run this command on your server:
apt-get install apt-transport-https ca-certificates
curl https://raw.githubusercontent.com/atech/postal/master/script/install/ubuntu1604.sh | sh
Note (this is one command line, so copy all and paste in putty and press enter)
Postal SMTP install command
The Setup is fully automated you will not need to do anything except waiting for a couple of minutes for the installation to finish.
When it’t Done, it will show you a success message “Installation complete“
Now Let’s create a user so we can login and manage out Postal Server through the web interface. Simply run the following command:
postal make-user
And this command will ask you to Enter Your Name, Email, and password. so write it down and press Enter.
Postal is Installed! So Simple
Configure Postal SMTP
Now, Open your Internet browser, and navigate to your Server IP URL or Subdomain like this:
https://YOUR_SERVR_ADDRESS
You will notics an SSL warning, It’s ok just proceed as you see in the image below:
SSL warning
And then the Postal Login Screen will open, enter your email and password that you created during the setup to login.
Postal Login
And Now, you are inside Postal, click “Add Organization” to add one.
Then Click on Build Mail Server and enter the name, and set it to live mode
Create Postal Mail Server
So Simple.
Postal Domain Configuration
Now, Click On Domains to add you domain name into Postal
Add Domain in Postal
Enter your Domain name that you want to use to send emails, and Click Create Domain.
Then, Postal will show you the Domain page with the records that you need to configure.
Postal DNS records
So, What you need to do simply, is to copy these records and paste in your DNS Zone. and then your server will be ready to send emails! but what are SPF and DKIM?
Dkim (DomainKeys Identified Mail) :
Let’s Start with DKIM, A DKIM record is also a text record in your DNS that holds a public authentication key. This key will be validated using a private key saved privately inside your server.
All emails will be signed, and this will avoid any alterations and protect your email originality, and this is very important for your server to archive high sending scores.
Watch this video for more info:
Setup Dkim For Postal
What’s nice about Postal, is that DKIM is already configured and the keys are generated, you just need to copy the DKIM record to your DNS Zone.
Postal DKIM record
SPF (Sender Policy Framework):
An SPF record is a TXT record that is added to your Domain DNS Zone and allows you to set the mail servers that are allowed to send emails from your domain.
Messages sent from a server that isn’t included in the SPF record will be marked as spam or rejected.
As an example, you can’t send an email from your own server and set your sending email as “mail@google.com,” you can’t use google’s domain. It indicates that you are trying to spam.
In the same way, you can configure SPF and prevent anyone from using your domain to send emails, So setting SPF is very important when it comes to making your domain trusted by other mailing providers.
To set up SPF. Open your DNS zone in and add the following record:
v=spf1 a mx ip4:XXX.XXX.XXX.XXX -all
*Replace with your VPS server IP.
Now only your server can send emails from your domain.
If you noticed, Postal will give you an example SPF to copy, and it looks like this:
v=spf1 a mx include:spf.postal.example.com ~all
This is just an example domain, and you need to change this in the postal config file to match your domain name. How?
Edit Postal config file.
To Edit the POstal Configuration File, we will need to connect to our server using a File manager to make things easy.
So, You can Use WinSCP, a free remote file manager, to connect and edit the files on the server.
Open WinSCP, and Connect to your server using the root credentials. and go to: /opt/postal/config Directory. Then Open the postal.yml file.
Postal yml configuration
Then, right-click and edit the file.
postal domain change
As you can see, just change the example domain with your domain name.
After that, you need to restart postal for the configuration to take effect.
So run this command on your server:
postal restart
And Refresh your web page, you must see now that example.com was replaced by your domain and you can simply copy the SPF record to your DNS zone.
Postal SPF record
Very Nice!
Now our Server is ready for testing.
Finally! Send a Test Email
Postal has built-in functionality to test sending emails, simply click on Messages, then on Send Message to test out Free SMTP server!
Send a test message
Wow!
Now you may be wondering how to use this SMTP as a relay to send emails from any email marketing application.
The Answer is simply by creating “Credentials” inside Postal to connect and authenticate to our Free SMTP Server.
Create Postal Credentials to Relay Emails
To create credentials, simply click on Credentials, then Add new Credentials.
For the Type, Select SMTP.
You can also select API if you wanna connect to postal through the API or develop your own application that works with Postal. Read more about the API here.
Enter a User (Anything you want)
And the Key, is the password, you can keep it as “automatically generated“
And that’s it, you can now use these credentials in any email marketing application.
Relay a Test Email
Simple, Go to SMTPER.NET and enter your server details as follows:
Test your SMTP
SMTP Host: Your Server IP or Domain.
Port: 25 or 2525
Login: The User You entered in credentials.
Password: The User Password.
So, these are the credentials that you can use in any Email Sender Application.
That’s it! I hope everything was simple and clear. we finish setting up the Free SMTP Server!
If you have any problems, you can open your questions email me dileep.rajput7@gmail.com
And if you like to get the Full Udemy Course On Build Your Own Cold Email Outreach System – Postal & Mautic, you can enroll now with a 95% Special Limited Time Discount.
Check Also: PowerMTA Mail Server Full Setup Guide
Before You Send!
Congratulations! You Setup your own Free SMTP Server using Postal. but before you start sending emails, you have to understand some crucial concepts and follow up on the guidelines to get the best delivery rates and reach the inbox!
Warming Up your SMTP server
When you build a New SMTP Server with a new IP Address, and Before You can Start Sending Your Email Marketing Campaigns, you have to warm up your IP Address.
What is Warming Up IP?
When you have a new Brand IP Address for your SMTP, this IP will have no Reputation on the internet, and ISPs (internet service providers) don’t know this IP.
So IP warmup is the practice of building Your Reputation on The Internet by gradually increasing the volume of mail sent with your IP address according to a predetermined schedule.
Example of warming up your server shown in the table below:
This Table shows a scenario if you wanna reach 1K emails per day with a good reputation. Please refer to my Warming up SMTP Guide for more details.
Also, you can watch my full video about Warming up here:
rDNS (Reverse DNS):
The reverse DNS is called a pointer record and is used to point your IP to your Domain, its the inverse of the regular DNS A record.
So when you call the IP, you will get the name. It is also an essential factor in setting up your mail server and increasing your sending score and reputation.
Learn more about rDNS here:
DMARC (Domain-based Message Authentication, Reporting & Conformance):
It is a Protocol that uses (SPF) and (DKIM) to determine the authenticity of an email message.
DMARC makes it easier for Internet Service Providers (ISPs) to prevent malicious email practices, such as domain spoofing in order to phish for recipients’ personal information.
It allows email senders to specify how to handle emails that were not authenticated using SPF or DKIM. Senders can opt to send those emails to the junk folder or have them blocked them all together.
To understand the importance of DMARC for your Online Business and how to set up, please watch this video:
MX Record
Mail Exchange (MX) records are DNS records that are necessary for delivering email to your address.
In simple DNS terms, an MX record is used to tell the world which mail servers accept incoming mail for your domain and where emails sent to your domain should be routed to. If your MX records are not pointed to the correct location, you will not receive an email.
Avoid Spam Factors
Mainly we have Four main factors the determines your spam score:
IP Reputation
SPF, DKIM, rDNS, and DMARC.
Message Body
Email List health.
The first two factors are explained above. we still have Message body and Email List Health.
Message body
Simply is the subject and the content of your email. Does it look spammy? Does it have any spammy keywords and triggers?? This determines your message score.
Be sure to avoid any of these while creating your Subject lines and Message bodies.
Check this article on Hubspot, to learn more about spam keywords.
You Maybe Also Interested in this article “How To Land Your Emails In Inbox? The Ultimate Guide!”
Email List Health
Simply it’s determined by two things:
Bounce Rate: How many emails are valid in your list.
Spam Traps: does your list contain any spam traps?
Learn more about spam traps and how to avoid in this video:
And always be sure to validate your email lists and clean it before sending any campaign. check my free online email validation service here.
I think you will be also interested in watching this video:
How to send 100K emails Daily to inbox.
Also, Join My Email Marketing Newsletter to Get exclusive Email Marketing Tips that I share only with my email subscribers.
Get Exclusive Tips That I Only Share With Email Subscribers
Subscribe Now!
No spam ever, unsubscribe anytime.
Postal Free SMTP Server Setup Video:
Optional: Secure with a Free SSL.
SSL certificates are used within web servers to encrypt the traffic between the server and client, providing extra security for users accessing your application. Let’s Encrypt provides an easy way to obtain and install trusted certificates for free.
Connect to your Server using Putty SSH client. and Let’s Start!
Step 1 — Install the Let’s Encrypt Client
Let’s Encrypt certificates are fetched via client software running on your server. The official client is called Certbot.
Install Certbot by running this command:
apt -y install certbot
Certbot is now ready to be used.
Step 2 — Get the SSL Certificate
But, before we get an SSL Certificate, we need to stop nginx service since its using port 80 which certbot will use. so Let’s stop it temporarily by running the following comnad:
sudo systemctl stop nginx
Now let’s install the certificate, run the following command:
certbot certonly --standalone -d postal.xmailing.me
Replace “postal.xmailing.me” with your domain.
And follow the wizard. Then certbot will issue a certificate for your domain.
Step 3 — Configure the SSL Certificate
After we got the SSL certificate, we need to configure it in our server.
Let’s start the nginx service again:
sudo systemctl start nginx
Now, Open WinSCP again to edit some files on our server.
Connect to your server, and go to /etc/nginx/conf.d directory.
In this folder, create a new file and name it: “postal.xmailing.me.conf“
Replace “postal.xmailing.me” with your domain.
Then, Simply copy the following code and paste inside the file.
server {
listen [::]:80;
listen 0.0.0.0:80;
server_name postal.xmailing.me;
return 301 https://$host$request_uri;
}
server {
listen [::]:443 ssl;
listen 0.0.0.0:443 ssl;
root /opt/postal/public;
server_name postal.xmailing.me;
ssl_certificate /etc/letsencrypt/live/postal.xmailing.me/fullchain.pem;
ssl_certificate_key /etc/letsencrypt/live/postal.xmailing.me/privkey.pem;
ssl_protocols TLSv1.2 TLSv1.1 TLSv1;
ssl_prefer_server_ciphers on;
ssl_ciphers EECDH+ECDSA+AESGCM:EECDH+aRSA+AESGCM:EECDH+ECDSA+SHA512:EECDH+ECDSA+SHA384:EECDH+ECDSA+SHA256:ECDH+AESGCM:ECDH+AES256:DH+AESGCM:DH+AES256:RSA+AESGCM:!aNULL:!eNULL:!LOW:!RC4:!3DES:!MD5:!EXP:!PSK:!SRP:!DSS;
location / {
client_max_body_size 50M;
try_files $uri $uri/index.html $uri.html @puma;
}
location /app/assets {
add_header Cache-Control max-age=3600;
}
location @puma {
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header Host $host;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Proto https;
proxy_pass http://127.0.0.1:5000;
}
}
And save the file.
The last step is to restart and enable nginx again. Simply run the following command:
systemctl restart nginx
Then this command:
systemctl enable nginx
And Awesome, Now you can test your secure Postal website!
Good Luck!
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DILEEP KUMAR RAJPUT
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