What Is an Email Server? How Does It Work?

ByHimadri Sharma


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Emails have become an essential part of our daily communication, used by billions of people worldwide for personal and professional purposes. While sending an email seems quick and straightforward, a complex infrastructure behind the scenes makes this possible. This complex infrastructure consists of email servers, acting like a digital post office that sends, receives, and stores emails. When you send an email, it goes through a series of servers to reach its final destination.

In this guide, we'll explore what email servers are, how they work, and how to set up an email server. By understanding the role of email servers, you'll gain a deeper appreciation for the technology that supports your inbox.

Table of contents

What is an email server?

An email server is a specialized computer system that manages the sending, receiving, and storage of email messages. It ensures emails are delivered from the sender to the recipient and any bounced emails are captured using SMTP.

Let me explain this plainly.

Consider a post office system where senders write a letter and drop it in a PO box. The postman collects the letters from the PO box and takes them to the main post office. The post office staff sorts the letters based on the recipients' addresses. These letters are then dispatched to the appropriate local post office in the recipient’s area. At the local post office, the letters are sorted again and handed to the local postman. The local postman delivers the letters to the recipients and collects signatures to confirm safe delivery.

In this process, the post office staff and postmen act like an email servers behind the scenes, managing all the logistics to ensure the letter reaches the recipient smoothly and securely.

How does an email server work?

Every time you write and send an email, several steps are involved in sending one email to ensure it reaches its destination. Think of sending an email like posting a letter. Just as you need a correct postal address, an email needs accurate recipient information, including the domain (the part after the "@" symbol, like "" in ""). Email servers use IP addresses and the Domain Name System (DNS) to ensure the email reaches the correct recipient. To understand the process here’s a simplified stepwise explanation:

Step 1: Sending to the SMTP server: After composing an email when you hit send, the sender’s server sends your email to a Simple Mail Transfer Protocol (SMTP) server. This server follows specific rules to transmit your email.

Step 2: Finding the address: The SMTP server knows the recipient's email address but not the exact location. It asks a DNS server for help.

Step 3: Role of the DNS server and record: The DNS server acts like an address book for the internet. It looks up the recipient's domain and provides the SMTP server with the correct IP address. For instance, an MX (Mail Exchange) record is a specific type of DNS record that identifies the mail server responsible for receiving email messages for a domain. It ensures proper email routing by specifying which server handles incoming emails for that domain.

Step 4: Making a connection: The SMTP server uses your internet connection to link to the recipient's SMTP server. They communicate to confirm everything is in order.

Step 5: Sending the email in pieces: For faster travel, the email is broken down into smaller chunks, like puzzle pieces.

Step 6: Checking for spam: The recipient's SMTP server checks the email for spam.

Step 7: Delivery to inbox: the mail client uses POP3 or IMAP to retrieve the email from the server. According to firewall settings and filter rules set by the recipient's email client, the server may also check for spam and sort the email into the appropriate folder (like inbox or promotions).\_3ZNrukxT2-T-BarEyhM2fJ-hQ7Q8T5Xs0KqVHrzzjRQerGFMTAUJZA3RrO5qns\_-YxzxWHWVgThe whole process happens very quickly, so the next time you hit send, you can appreciate the amazing technology that delivers your message!

For further insights, check out this detailed guide on SMTP with the Email Marketers

Dedicated vs shared email servers

You might come across businesses that have private email domains and servers for themselves. This means they have exclusive control over their email operations. In contrast, some email servers are shared between multiple senders, managed by a third-party provider.

The server that is exclusively allocated to one user or organization is considered a dedicated server or private email server. Whereas, servers that are shared among multiple users are considered shared (non-dedicated) servers

Now, let's break down the key differences between dedicated and non-dedicated email servers:

Aspect Dedicated email server Shared email server
Ownership Owned and operated solely by one user or organization Shared among multiple users or organizations, often managed by a third-party provider
Control Offers complete control over server configuration and resources Limited control as resources are managed by third-party
Cost Higher initial setup and maintenance costs due to its exclusive nature Lower initial setup costs with ongoing fees for shared services

It is highly recommended to have dedicated email servers because the kind of control, and reliability the dedicated servers offer not only benefit businesses but also streamline their email communication and ensure optimal deliverability.

How to set up a dedicated email server?

Setting up a dedicated email server involves several essential steps to ensure its proper functioning and security. Here are the key steps to follow:

Step 1: Procurement

Choose a reliable server provider for your email needs. An on-premise dedicated email server is physically located at your office and requires you to handle hardware and software purchases, installations, maintenance, and technical management.

Alternatively, you can consider having a cloud-based dedicated email server, hosted by a third-party provider, is accessed online for a monthly or annual fee, and relies on the provider for data and security management

Do not forget to grab a custom domain name from a registrar.

Step 2: Consider OS compatibility

Many private server providers offer a variety of operating systems to choose from. For email servers, Linux distributions like Ubuntu or CentOS are popular choices because they're known for stability and are open-source, giving you more control and customization.

Step 3: Select email server software

The open-source world offers a variety of email server software, each catering to different needs. Here are some popular options to consider:

Postfix: Renowned for its stability and performance, Postfix excels at handling high email volumes. However, it requires a more technical setup.

Courier-MTA: Another robust option, Courier-MTA offers a good balance of features and ease of use compared to Postfix.

Other choices: Explore other options like Dovecot (IMAP/POP3 server) and Roundcube (webmail client) to build a custom solution.

Step 4: Installation and configuration of server software

This step requires the most technical expertise. The specific setup process varies for each software. It's best to refer to the official documentation for detailed instructions. Generally, you'll be setting up:

Mail exchange protocols (SMTP, POP3, IMAP): These define how emails are sent and received.

User accounts: Create accounts for authorized users.

Security settings: DomainKeys Identified Mail (DKIM), Sender Policy Framework(SPF), Domain-based Message Authentication, Reporting, and Conformance (DMARC) are three technologies that are commonly used by internet service providers to protect users from email fraud. Implement these settings to improve email deliverability and combat spam.

Step 5: Setting up email delivery (DNS management)

Update your domain's DNS records to point your custom email address (e.g., [email address removed]) to your private server's IP address. This ensures emails sent to your domain reach your server.

Step 6: Securing your email server

Enable firewall rules: Restrict incoming and outgoing traffic on your server's firewall. Only allow connections on ports essential for email protocols (e.g., SMTP, POP3, IMAP). This strengthens your server's security.

Maintain software updates: Regularly update your server's operating system, email server software, and any additional packages. This helps patch security vulnerabilities and keeps your system protected.

Step 7: Email client configuration (accessing your email)

Once your server is set up, configure your preferred email client (e.g., Thunderbird, Outlook) with the appropriate server settings. This allows you to send and receive emails using your custom domain address.

Do not forget to set up server settings, including security measures such as SSL/TLS certificates, spam filters, and user permissions, and start sending your emails.

How to pick the right email server software

When setting up your email server, choosing the right email server software is crucial. There are several options available, ranging from open-source software to commercial solutions. Consider the following factors when selecting email server software:

Open source vs commercial: Open-source software is typically free, customizable, and supported by a community, making it cost-effective and flexible, ideal for tech-savvy users and budget-conscious businesses. In contrast, commercial software is usually closed-source with paid licenses, offering user-friendly interfaces, additional features like collaboration tools, enhanced security, and professional support, making it suitable for businesses that prioritize ease of use, strong security, and reliable support.

Security: Choose software with strong spam filtering, encryption, and authentication protocols.

Scalability: Consider the scalability of the software to accommodate your current needs, projected email volume, and potential future growth.

Compatibility: Ensure that the software is compatible with your operating system

Ease of use: Evaluate the user-friendliness of the software, especially if you have limited technical knowledge.

Support and updates: Consider the availability of customer support services and regular software updates to ensure the security and stability of your email server. Additionally, must check their historical deliverability rates.

By carefully evaluating these factors, you can choose the email server software that best suits your needs, whether it's for personal use or for your business.

Strategies for optimizing your email server

Here are some proven strategies to optimize your email server:

Hardware and software upgrades

Periodically upgrade your email server hardware and software components to keep pace with evolving technology and meet growing demands. Upgrading to newer, more efficient hardware and software versions can significantly enhance server performance and reliability.

Implement email filtering and spam protection

Utilize advanced email filtering and spam protection solutions to prevent malicious emails, phishing attempts, and unwanted spam from reaching users' inboxes. Effective filtering reduces the risk of security breaches and improves overall email server performance.

Optimize server configuration

Fine-tune server configurations, including mail transfer agent (MTA) settings, DNS configurations, and email routing rules, to optimize email delivery and ensure efficient resource utilization. Proper configuration can minimize delivery delays and improve server responsiveness.

Enable compression and caching

Enable compression and caching mechanisms to reduce bandwidth usage and speed up email transmission. Compression techniques such as gzip compression can significantly reduce the size of email attachments, resulting in faster delivery and reduced server load.

Implement TLS encryption

Secure email communications by implementing Transport Layer Security (TLS) encryption for incoming and outgoing emails. TLS encryption encrypts email data in transit, protecting it from interception and unauthorized access, thereby enhancing email server security.

Regular maintenance and updates

Perform regular maintenance tasks such as software updates, security patches, and system optimizations to keep your email server running smoothly and securely. Regular maintenance helps prevent potential vulnerabilities and ensures optimal server performance.

Backup and disaster recovery planning

Implement robust backup and disaster recovery plans to protect against data loss and ensure business continuity in the event of server failures or disasters. Regularly backup email data and store backups in secure off-site locations to facilitate quick recovery in case of emergencies.


Optimizing an email server improves performance by streamlining processes and maximizing resource utilization.

Optimizing an email server can enhance security by implementing encryption, authentication, and intrusion detection measures.

Hardware and software upgrades should be performed regularly to ensure optimal performance and security, typically following industry best practices and manufacturer recommendations.

Email filtering and spam protection provide benefits such as reducing inbox clutter, preventing malware distribution, and safeguarding sensitive information.

Regular maintenance is important for email servers to ensure smooth operation, address vulnerabilities, and prevent downtime or data loss.

Essential elements of a backup and disaster recovery plan include regular backups, off-site storage, redundancy measures, and documented procedures for restoring operations in case of emergencies.

Ensure email server security by implementing access controls, encryption, regular audits, software patches, and employee training on cybersecurity best practices.

Whether you need a dedicated email server depends on factors like privacy, customization, and control preferences, but using Gmail or Outlook can suffice for many users' needs.

An email server handles the sending, receiving, and storage of emails, while a web server serves web pages and content over the internet.

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