Getting Started with hMailServer

Microsoft Outlook

hMailServer is a free email server for organizations, businesses, and individuals which is easy to install and simple to use. Find out how to install and configure hMailServer in this overview.

What is hMailServer?

Have you ever wondered if there were any decent alternatives to Microsoft Exchange as your mail server? Well, there is! hMailServer is an open-source, free email server for Microsoft Windows environments.

Honestly, I wasn’t aware of this solution. It was first developed in late 2002 by Martin Knafve. Since that time, it has become one of the most popular email servers for Windows.

After looking over its features, it does remind me of MDaemon back in the 90s. Those were the days…

The core features of hMail Server

The main components of hMailServer include a simple installation and configuration procedure, built-in security measures (support of SSL certificates, integration with virus scanners, email black list servers, and SPF/MX lookups), integrations with other software products via a COM library, and many more. I’ll get into more of these features later on.

Is hMailServer secure?

The security of hMailServer depends on what steps you take during its initial setup, installation, and configuration. Out of the box, it won’t be secure. There will be no secure email transfer occurring at all.

The default ports like 110 (POP3), 25 (SMTP), 143 (IMAP) are insecure. However, when you add an SSL certificate and create new bindings in the software, you’ll gain secure transfer of email via ports 995 (POP3 SSL), 465 (SMTP SSL), and 993 (IMAP SSL).

I highly recommend you purchase a 3rd-party SSL certificate for the hostname of your new hMailServer before sending or receiving emails, especially for a professional business email account. Leaving an insecure POP3/SMTP email server on the Internet is not the smartest thing to do these days.

How to install hMailServer

Next, I’ll go through the basics of the installation of hMailServer.

Ready to download hMailServer? Great. You can visit the download page of hMailServer to obtain the installation program via this download link. As of this writing, I’ll be installing version 5.6.8 (build 2574) released in October of 2021.


There are a few high-level prerequisites you’ll need to consider when planning your installation. I cover hardware, software, and database requirements below. But here are a few others not to forget.

Network and port requirements

You need to make sure some combination of these ports are open on your server and in your firewall-protected network.

  • 25 (SMTP)
  • 465 (SMTP SSL/TLS)
  • 587 (SMTP Send)
  • 110 (POP3)
  • 995 (POP3 SSL/TLS)
  • 143 (IMAP)
  • 993 (IMAP SSL/TLS)

Also, you will be needing a few DNS records on the Internet to facilitate other email servers being able to route your email to your hMailServer. This includes MX records, A records, and maybe even a CNAME record. I’ll address this down below.

Hardware requirements

There really aren’t any ‘hard’ requirements. Looking at the software’s homepage, there are no specific memory, CPU, disk storage requirements. I would imagine 4GB of memory would be a good minimum, at least a 2-core server or 2 vCPU virtual machine (VM) would suffice, for the basics.

If you are planning to use this to handle hundreds of users, then you would want to make sure you have 8, 16, or more GBs of RAM, plenty of disk storage, and 4, 6, or 8+ vCPUs to handle the load. Not only will your users be making POP3/IMAP connections to the server, but the server will also be receiving inbound emails and sending emails out to the Internet.

Here are the ‘supported’ operating systems to run version 5.6.x of hMailServer:

  • Windows Server 2012
  • Windows Server 2008
  • Windows Server 2003
  • Windows 7
  • Windows Vista
  • Windows XP Professional SP3

Disclaimer: Only the top version of Windows above is supported by Microsoft (and Windows Server 2012/R2 goes out of support in October 2023!). I highly suggest NOT using it. Let me trim this down to a list that you should use:

Although these newer server OSes aren’t listed on their homepage, you should feel confident installing the software on newer versions of Windows Server. I’ll be installing the software on a Windows Server 2022 VM.

Database requirements

You have a few options when it comes to database engines to house your email configuration and mailbox databases. hMailServer comes with SQL Server Compact Edition (CE) that you can use for testing and non-commercial use cases. If you plan to create a commercial email server, you need to choose one of these external database engines:

And, to add to this, I would highly assume you could use a supported version of Microsoft’s SQL Server, too, including:

  • SQL Server 2019
  • SQL Server 2017
  • SQL Server 2016

And, lest I forget, there is one more lovely prerequisite you need to be aware of: ‘.NET Framework 2.0’. Yes, this software was built against the .NET Framework 2.0 SDK, so we need to make sure we have the runtime installed. Thankfully, we simply need to install the ‘.NET Framework 3.5 Feature’ as this includes .NET 2.0 and 3.0. Let me show you how to do that with PowerShell.

Launch an administrative PowerShell prompt by right-clicking on the Start button and clicking ‘Windows PowerShell (Admin)’.

Enter the following command.

Install-WindowsFeature Net-Framework-Core
Installing .NET Framework 3.5 (and version 2.0 & 3.0)
Installing .NET Framework 3.5 (and version 2.0 & 3.0)

And, we’re all set!

The .NET Framework 3.5 is now installed
We have .NET Framework 3.5 installed, ready for the install!


Let’s go through the installation wizard next. Double-click on the downloaded file to start the Setup program.

Starting the Installation of hMailServer
Starting the Installation

Click Next and then choose to accept the license agreement.

Accept the license terms
Accept the license terms

If you want to change the destination folder for the software, go ahead. The default location is in the program files folder on your C: drive. Then, click Next.

Option to change the installation folder
Option to change the installation folder

I recommend keeping the ‘Full installation’ type. Click Next.

Choosing installation options
Choosing installation options

Choosing the database server type, you can choose between the built-in (Microsoft SQL Compact), or an external choice (full MS SQL Server, MySQL, or PostgreSQL). For these purposes, I’ll keep the built-in and click Next.

Choosing the database installation server type
Choosing the database installation server type

You can change the name of the Start Menu folder if you want. Click Next.

You can change the name of the Start Menu folder if you want
You can change the name of the Start Menu folder if you wish

Here, you’ll need to enter an administrative password for the administrative user being created by Setup. Be sure to make this password secure, and don’t lose it! You’ll need it to configure the software.

Enter a secure administrator password for the software
Enter your administrator password for the software

Here’s the ‘Ready to Install’ screen. If you need to make any changes, feel free to go back and make them, then click Install.

Summary Screen - Ready To Install
Summary Screen – Ready To Install

Congratulations, the hMailServer software is now installed.

The hMailServer software is now installed
The software is installed!

To handle server administration, let’s launch ‘hMailServer Administrator’ from the Start Menu.

Launch 'hMailServer Administrator' to handle server administration
Launch ‘hMailServer Administrator’ to handle server administration

Go ahead and check the box ‘Automatically connect on start-up’ to bypass this in the future. If you happen to have a remote hMailServer, you could enter its hostname, Fully Qualified Domain Name (FQDN), or IP address here using the administrative management tools.

Click Connect and enter the hMailServer admin password you created during Setup. Here’s the Welcome page.

Connect with the admin password and reach the welcome page.
Welcome to hMailServer!

DNS configuration

As I mentioned above, there are a few DNS records that will be required for the full functionality of the software to work. First, let’s handle external records (on the Internet). The first is an MX record.

An MX DNS record is a record that tells how/where to deliver an email to a specific domain. This record needs to point to the ‘external’ [IP] Address of your hMailServer. As an example, an email destined to could go through

Next, you would need an external A record. This tells DNS servers what IP address is associated with

Your network administrators would be able to assign an external IP address for your hMailServer. A common scenario is having a ‘one to one’ NAT setup on your edge firewall. This allows inbound traffic to your hMailServer’s external IP Address to ‘translate’ to its internal (LAN) IP Address (say,

Now, to cover internal records, the simplest scenario is an A record for your hMailServer’s hostname pointing to its internal (LAN) IP Address. You could have ‘hmailserver01.reinders.local’ point to

This is the absolute simplest setup. You can do additional research on more sophisticated DNS configurations.

Firewall / Router ports

As I hinted at above, you will need a few ports open on your edge router or firewall to allow outgoing traffic to flow between your hMailServer and the Internet. Let’s assume you’re using only secure (SSL) traffic. In that case, you could ask your network team to open the following ports inbound from the Internet to the local (LAN) IP address of your hMailServer.

  • 465 (Secure SMTP)
  • 995 (Secure POP3 – If needed)
  • 993 (Secure IMAP)

Specifying a public host name and SMTP relayer

To allow for inbound email traffic from the Internet, you need to specify a public hostname of the computer you installed hMailServer on. You do that via Settings -> Protocols -> SMTP.

Next, click on the Delivery of e-mail tab.

Configuring email delivery
Configuring the nuts and bolts of email delivery

In the ‘Local host name’ field, I could enter ‘ Now, in order for that to work, I would need to make sure I had an external (Internet) DNS A record for that hostname to point to the external IP address of my server.

In terms of outbound email, it’s typical for company networks to block port 25 outbound directly from a server to the Internet. This is done for security purposes. However, you can check to see if your server has the ability to send on port 25 or not.

Go to a command prompt/Terminal and enter this command:

telnet 25
This command shows outbound traffic on port 25 is blocked/unavailable
This shows outbound traffic on port 25 is blocked/unavailable

This means you can’t send email directly from the server you’re on. It helps to alleviate rogue SMTP servers from spamming the Internet and blocking out one or more of your external (public-facing) IP addresses.

So, we can use an SMTP relay to send emails to your ISP’s email server. Letting internet service providers handle this task is very wise and efficient. They can then handle the task of determining where the emails should go (based on DNS and MX record lookups) and deliver the emails. You can specify these SMTP settings on the same page as above.

Under the ‘SMTP Relayer’ field, enter the server in the ‘Remote host name’ field and the TCP/IP port. For example, the company that provides my Internet connection (ISP) is AT&T. I looked up online what their email settings are for email applications:

  • For sending email, the DNS name is So, I would enter that in the Remote host name field, enter port 465 or 587 (for Secure SMTP or SMTP Submission), and then check the box for ‘Server requires authentication’.
  • Next, I would enter my main AT&T account details, username and password in the respective fields.

Adding a new domain and accounts

Alright, let’s add our domain name to the system. We can do this by clicking the ‘Add domain’ button on the Welcome page, or by clicking on Domains and clicking the ‘Add…’ button.

Adding an email domain to hMailServer
Adding an email domain to hMailServer

I’ll go ahead and enter an example domain and click ‘Save’.

We've added our '' domain
We’ve added our ‘’ domain

Next, we’ll add a few users. Under our domain name, click Accounts, then on the ‘Add…’ button. I’ll add a few users here by adding the email address, the password, a maximum size for messages (in MB), and any other features required.

We've added three user accounts to hMailServer
We’ve added three user accounts

Connecting hMailServer with Active Directory

To help ease the administrative burden around managing accounts and passwords, you can integrate hMailServer with your local Active Directory (AD). You can modify users or create new users using the ‘Active Directory’ tab.

The first scenario is if you have an existing account and want to integrate it with AD. To do so, click on the account and click the ‘Active Directory’ tab. Then, click the checkbox next to ‘Active Directory account’, enter the AD domain in the Domain box, and the username (SAMAccountName) in the ‘User name’ box. Then, click Save.

This will facilitate the credentials when the user checks for emails in their email application. They will be able to enter their AD username and password to retrieve their email from hMailServer.

The other main scenario allows you to add an existing AD user into hMailServer. To do this, right-click on the ‘Accounts’ folder, and choose ‘Add AD account’. Next, you choose your AD domain from the ‘Domain:’ dropdown, then select your account from the ‘Accounts:’ field.

Encrypting emails with SSL certification

As you’ve noticed thus far, the initial setup and configuration of the server does not include secure email traffic. In order to button up your new email server, you’ll need an SSL certificate for authentication and encryption from a trusted Certification Authority (CA) like DigiCert,, or to name a few.

You can follow the instructions from the SSL cert provider to obtain your certificate. Be sure to get the SSL cert in the PEM format, compatible with hMailServer. You’ll need the file and the private key files available.

To import your new certificate, go to Settings -> Advanced -> SSL Certificates. Click ‘Add…’

Adding an SSL Certificate for secure email communications
Adding an SSL Certificate for secure email communications

Type in what you want the Name to be. It’s probably best to use your certificate’s ‘Subject Name’. Then, browse to the ‘Certificate file’ and the ‘Private key file.’ Next, click Save.

Now that the SSL certificate is added, you need to ‘bind’ it to your secure ports. In the Advanced section, browse to ‘TCP/IP ports’.

TCP/IP ports are where you bind the new SSL certificate
TCP/IP ports are where you bind the new SSL certificate

Because we are using secure ports, we need to add one. Click ‘Add’ and enter the SMTP information per the screenshot.

The only other step you would take, of course, is to choose your new SSL certificate from the ‘SSL Certificate’ dropdown. You can perform the same steps for POP3 and IMAP by using the same essential fields, the same certificate, but use ports 995 for POP3 and 993 for IMAP. Easy as pie!

Setting up an account in Outlook or other email clients

There are many email client programs compatible with IMAP/POP3/SMTP including Microsoft Outlook, even Outlook Express. Let me try another alternative, Mozilla Thunderbird, to at least verify the server settings get discovered correctly. After downloading and installing Mozilla Thunderbird from this link, I launched it and entered some of the basic information.

Setting up an hMailServer account in Mozilla Thunderbird
Going through the initial setup of my account in Mozilla Thunderbird

Although not everything worked during the first test, I went ahead and clicked the Re-Test button at the bottom after entering the hostname as ‘hmailserver01’, my email address – ‘[email protected]’, and IMAP as the protocol. It then ‘probed’ the server and filled in the rest of the information correctly.

Thunderbird then probed the hMailServer and verified/rectified some of the fields
Thunderbird then probed the hMailServer and verified/rectified some of the fields – We’re good!

After I clicked ‘Done’, I got the following warning message.

without SSL encryption Thunderbird shows a warning
As I said, without SSL encryption, you’re asking for trouble in using email without secure traffic…

This confirms that we are not using encryption to make the connection to the email server. It’s outside the scope of this article to go through all the necessary steps to enable SSL encryption on our hMailServer.

Anyway, we have Thunderbird configured with our email account!

The new email account is now configured
The new email account is done!

And, just to confirm that checking emails is working, I went to Settings -> Logging, checked the ‘Enabled’ box at the top, also checked ‘Application’ and ‘IMAP’, and clicked Save.

I then went to Thunderbird and clicked the ‘Get Messages’ at the top. I went back to hMailServer, clicked on ‘Show logs’, and saw our successful IMAP connection attempt.

Logs from hMailServer with our inbound IMAP attempt from Thunderbird
Logs from hMailServer with our inbound IMAP attempt from Thunderbird


As you can see, setting up hMailServer is considerably less daunting than setting up Microsoft Exchange Server. You only really need some external DNS records and an SSL certificate for secure encryption and email traffic, and you can have this solution up and running in only an hour or two with the info provided here.

As a reminder, these are only the basics of what you can do with hMailServer. There are integrations with 3rd-party webmail solutions like RoundCube and SquirrelMail. There are different hMailServer services, too, including Spam protection, built-in backup, server-side rules, and more.