In this Step by Step Guide, I will show you how to setup an SMTP server and connect it to your email marketing applicaiton to send emails with no limits*.
There are several methods to build SMTP servers, in this guide I will build the SMTP server using a free WHM (web hosting manager) software called “Webmin”. It’s Like “cPanel” but for free!
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.
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:
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:
- 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.
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:
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 an don’t block it, because some companies do this to protect from spammers.
Here is a list of some companies that allows port 25 by default:
- Host wind.
- 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.
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.
First, check your hostname:
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 server.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.
*server is in my case, you can choose whatever you want for your server name.
Done? ✔️ Let’s continue.
Setup 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 the WHM (Webmin) Software.
We have several SMTP Software like PowerMTA, Postal, Exim, Postfix…
In this guide, we will be using Postfix as our SMTP software (service). and to make things easy and automated I will install a Web Hosting Manager (Webmin) which installs and configures Postfix automatically (No need for manual configuration and hard stuff).
To Install Webmin, simply run this command on your server:
this command will download the installation script, now let’s start the setup by running this command:
sudo /bin/sh install.sh
So Simple 👍
Just wait for the installation to finish, it may take several minutes. Then you will see this success message:
Very Nice, Now Open your Web Browser and Navigate to your Server URL To Configure.
The URL will look like this: https://YOUR_SUB_DOMAIN:10000
Webmin uses Port 10000, so be sure to add “:10000” after your server address.
*Note: sometimes Port 10000 may be blocked by the firewall, so you need to open it.
When you open Webmin for the first time, you will see an SSL warning Message, just click continue anyway:
Then the login screen will appear:
Great! Just enter your root username and password, and log in!
From now on, everything will be managed through the Web interface, so Things will be simple. ✔️
Webmin Basic Configuration
When you log in for the first time, you will see the post-installation wizard.
Set the options as the following:
- Preload Virtualmin Libraries: YES
- Domain Lookup Server: YES
- ClamAV Server Scanner: NO (It will use a lot of Resources, Turn On if you have a lot of CPU and RAM)
- Spamassassin Filter: NO (It will use a lot of Resources, Turn On if you have a lot of CPU and RAM)
- MariaDB/MySQL Server: YES
- PostgreSQL: NO
- Set MySQL password: “ENTER_YOUR_SQL_PASSWORD”
- MariaDB/MySQL Database Size: Medium
- DNS Configuration: check the box “Skip check for resolvability“, and click next as in the image below:
- Password Storage mode: Choose Any, for Higher Security, Select Hashed.
Now, click on re-check and refresh configuration, and wait for the operation to finish. Then you will see this success message:
Create your Free Business Email
Now our server is ready for the real part, we can create the business email address that we will use as the sender address. to do so, we need to create a virtual server inside webmin using our Domain name.
Create Virtual Server
Click “Create Virtual Server” on the upper left corner of the screen as shown in the image below:
Now simply you need to fill your domain name, Description, and password for this virtual server.
And Click Create Server ✔️
Create the User Account Email Address
Now we have a virtual server, simply click on Edit users to the left.
Then click “Add a User to this server“, the new user wizard will open:
Enter any Email you want, like support, mail, admin, or whatever business email you want. Then Enter the name, and the password.
Then click Create.
You Have Now a Free Business Email! ✔️
We are done! your SMTP Server is now ready.
Before You Send!
Congratulations! You Setup your own SMTP Server using Webmin. 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:
|Warmup Day||Emails To Send|
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:
Configure SPF, DKIM, rDNS, DMARC, and MX.
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 “firstname.lastname@example.org,” 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.
Dkim (DomainKeys Identified Mail) :
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 Webmin Postfix:
To Configure Dkim, we need to configure it on our Server First, then copy the public key to our DNS zone.
Then Click on “Domain Keys Identified Mail” under “Email Settings“
Then Click Install Now. After the installation finishes, go back again to ” Domain Keys Identified Mail” and you will the options to generate your keys.
Keep the Defaults, and then click Save.
Now, Click on DNS records under Server Configuration.
Just Copy the Dkim record and create it in your DNS Zone of your Domain, in my case it’s Godaddy.
Great! DKIM is Configured. ✔️
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:
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.
Set the MX
Go to your DNS Zone and Create a new MX record and point to your server domain like this:
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.
Simply is the subject and the content of your email. does it look spammy? does it have any spammy keywords and triggers?? this what 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:
Follow up My Youtube Channel For Daily Awesome new videos about Email Marketing, Digital Marketing, and Online business stuff to Grow Online.
Also, Join My Email Marketing Newsletter to Get exclusive Email Marketing Tips that I share only with my email subscribers.
Finally! Send a Test Email
Now we Setup our SMTP Server. We are ready to send our first email. How to test our server?
Simple, Go to SMTPER.NET and enter your server details as follows:
- SMTP Host: Your Server IP or Domain.
- Port: 587
- Login: The Email Account You created.
- Password: Your Email Account 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 setup the SMTP Server!
If you have any problems, you can open your questions on H-asnwers.com
And if you like to get the Full Udemy Course On How to Build SMTP Server and Send Unlimited Emails, you can enroll now with a 95% Special Limited Time Discount.
Check Also: PowerMTA Mail Server Full Setup Guide 👈