What are email servers? The 3 main types explained

Where would we be today without email servers?

Email servers are responsible for sending, receiving, and storing emails.

Without email servers, we couldn’t send or receive emails.

In this post, we’ll explain what email servers are and discuss their essential functions.

What kind of email servers are there? ⁉️

There are three main types of email servers you need to know.

Let’s quickly review them.

SMTP servers

SMTP means Simple Mail Transfer Protocol.

SMTP servers are responsible for sending outgoing emails.

When you click “send” on an email you just composed, your email client connects to an SMTP server to send the email to its destination.

POP3 servers

POP3 stands for Post Office Protocol version 3.

These servers retrieve and download incoming mail to your email client.

Once downloaded, the messages are typically deleted from the server. There’s no synchronization with POP 3.

POP3 servers are used less and less nowadays for incoming email due to the superior functionality of IMAP servers.

IMAP servers

IMAP stands for Internet Message Access Protocol.

IMAP servers also retrieve incoming mail, but unlike POP3, the emails remain on the server, and your email account can be synced from any device.

Any changes you make in your email client will also be reflected on the server level—even the folder structure.

Because of this advanced synchronizing, IMAP servers are used more than POP3 servers nowadays.

Email servers agents 🕵🏾

Email servers have several agents working for them.

These agents aren’t like James Bond. Instead, they’re software that performs various tasks within the email server system.

We’ll explain them below:

MTA

The Mail Transfer Agent is responsible for transferring emails between servers.

MTA handles the sending part of the SMTP protocol.

It accepts emails from users or other servers and routes them to their appropriate destinations.

Its main job is ensuring correct delivery to the recipient’s mail server—even if their email is hosted on a different email service provider.

MDA

All these letter combinations might have you thinking we’re dealing with illegal substances here.

However, MDA stands for Mail Delivery Agent. Fortunately, we’re dealing with the delivery of email and not some unlawful chemicals.

You see…

MDA is responsible for the final stage of email delivery. It delivers incoming emails to the user’s email account.

When the MTA (not MDA!) receives an email for a local user, it lets the MDA take it to the appropriate mailbox.

MUA

MUA stands for Mail User Agent. It’s the user’s email client.

Think Outlook, Thunderbird, or web-based clients like Gmail and Yahoo Mail.

Users use it to send, receive, and manage their emails.

The MUA connects to the email servers (SMTP for sending, and IMAP or POP3 for receiving email).

It works as a user-friendly interface, without the user being aware of the complex underlying protocols and components.

Email server security 🪪

Let’s face it.

To say email servers handle sensitive information is an understatement.

Just think of all the personal details and business communications present in emails.

And that’s precisely the stuff that interests cyber criminals!

Securing email servers is of the utmost importance to protect the integrity of email communications and prevent cyber crimes.

Some common security threats are:

• ⚠️ Spam: Unsolicited emails can contain malicious content or links, including viruses, trojans, and ransomware. Additionally, spam can overwhelm email servers and consume its resources.
• ⚠️ Phishing: Fraudulent emails that look legitimate can deceive users into revealing sensitive personal information such as login or financial details.
• ⚠️ Brute-force attacks:  Criminals launch these attacks to gain unauthorized access to email accounts. Brute-force attacks work by automatically guessing usernames and passwords.

The best practices for email server security must be followed to maintain tight security.

Here are the three most important ones:

1. ➡️ Using encryption: Security protocols like TSL or SLL make it significantly harder for anyone to spy on the data transmitted through email servers.
2. ➡️ Having strict user verification and permissions: Strong password policies and multifactor authentication help keep the bad guys out of private email accounts.
3. ➡️ Keeping server software and operating systems up-to-date: Regularly checking for and applying security updates is of the utmost importance for email server security. Failing to do so may expose the servers to cyber threats like malware and attacks targeting software vulnerabilities.

Adding email servers to lemlist ⚙️

You can add almost any email account to the multichannel outreach tool lemlist.

Which means it’s also easy to add most email servers to it.

In your lemlist account settings, go to “Sending settings” and click “Connect new email addresses.”

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Next, when you’re asked to choose your email provider, you hit the “Other email provider (SMTP/IMAP)” button.

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Then, you have to log in to your email account and click “Connect.”

Finally, you must add the SMTP and IMAP server details to complete the configuration:

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Invisible force 💪🏾

Email has become an essential part of everyday communication.

We probably couldn’t live without it in our personal and especially professional lives.

But we never stop to think about how it all works behind the scenes.

We hope to have enlightened you a bit on how email servers work tirelessly to ensure your messages reach their destination reliably and securely.