What Is a Mail Server and How Do Mail Protocols Work?

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Every time you send or receive an email, there’s an invisible system working behind the scenes to make sure your message reaches the right place. That system revolves around mail servers and the protocols that connect them.

In this post, we’ll start by explaining what a mail server actually is, then explore the main protocols (SMTP, POP3, and IMAP) that make modern email communication possible.

We’ll also look at how FastHostCity provides domain-based mail servers that look like mail.domain.tld, giving your email a professional edge.

Not sure what a TLD means? Read more here.

What Are Mail Server Protocols?

Mail server protocols are sets of communication rules that define how mail clients (like Outlook, Apple Mail, or Thunderbird) and mail servers (like Gmail or FastHostCity’s servers) interact with each other.

Think of them as the postal routes and delivery rules of the digital mail world.

There are three main types of protocols:

  1. Sending protocols (for sending email)
  2. Receiving protocols (for downloading or syncing email)
  3. Support protocols (for lookup and security functions)

1. Sending Mail: SMTP (Simple Mail Transfer Protocol)

SMTP is the workhorse that handles sending emails. When you compose and send a message, your mail client uses SMTP to push it to your outgoing mail server. That server then delivers the message to the recipient’s mail server.

  • Default Ports:
    • 25: Server-to-server delivery (mainly used between mail servers)
    • 587: Submission from client to server (modern standard)
    • 465: SMTP over SSL (legacy but still supported)

SMTP ensures your outgoing emails leave your server and find their destination securely.

Example:
If you own a domain with FastHostCity, say mybrand.com your outgoing mail server would typically be mail.mybrand.com, configured with SMTP authentication and encryption.

2. Receiving Mail: POP3 and IMAP

Once an email reaches your mail server, it’s stored there until your mail client retrieves it. That’s where POP3 and IMAP come in.

POP3 (Post Office Protocol v3)

POP3 is the older, simpler protocol for downloading emails from the server to your local device.

  • Ports: 110 (default), 995 (secure SSL/TLS)
  • Behavior: Downloads messages — and usually deletes them from the server afterward.
  • Best for: Single-device setups or users who prefer storing mail locally.

Example: Old-school desktop clients or low-storage hosting setups often use POP3.

IMAP (Internet Message Access Protocol)

IMAP is the modern way to synchronize emails across devices.

  • Ports: 143 (default), 993 (secure SSL/TLS)
  • Behavior: Keeps messages on the server, syncing read/unread status and folders across devices.
  • Best for: Multi-device access (phones, tablets, laptops, etc.)

With IMAP, your email stays organized and accessible anywhere.

3. Supporting Protocols Behind the Scenes

Several other technologies quietly support the email system:

  • DNS (Domain Name System): Uses MX (Mail Exchange) records to locate the right mail server for a domain.
  • LDAP (Lightweight Directory Access Protocol): Used for corporate address books and user lookups.
  • HTTP/HTTPS: Powers webmail services like Gmail or FastHostCity’s webmail portal.

These make sure that when you send an email to someone@domain.com, it actually knows where to go.

How FastHostCity Handles Mail Servers

At FastHostCity, every domain you register can have its own custom mail server  formatted as:

mail.domain.tld

For example:

  • mail.mybusiness.com
  • mail.fastbrand.net

This makes your email look professional and ensures full control over your communication setup.
FastHostCity’s servers support SMTP, IMAP, and POP3, all with secure SSL/TLS encryption.

That means you can use any mail client  Outlook, Apple Mail, Thunderbird, Gmail or even your smartphone  and enjoy reliable, synced email without worrying about lost messages or insecure connections.

FastHostCity Mail Server Configuration for Gmail & Other Clients

You can access your FastHostCity-hosted email in several ways:

  • Through Gmail (using POP3/IMAP + SMTP)
  • Through any mail app (Outlook, Apple Mail, etc.)
  • Or directly via webmail at https://yourdomain.tld/roundcube

Accessing Email via Webmail (Roundcube)

If you prefer checking email through your browser, FastHostCity provides a built-in webmail system powered by Roundcube.

Just go to: https://yourdomain.tld/roundcube

Setting up your email in a Gmail App or Other Email Client

If you’re setting up your domain email in the Gmail mobile app or another client (like Apple Mail or Outlook), use the following configuration:

Incoming Mail (IMAP or POP3)

Setting IMAP POP3
Server mail.yourdomain.com mail.yourdomain.com
Port 993 995
Encryption SSL/TLS SSL/TLS
Username you@yourdomain.com you@yourdomain.com
Password (your email password) (your email password)

 

Final Thoughts

Email might feel instant, but behind every “Send” and “Reply” are a series of complex, well-orchestrated protocols. SMTP, IMAP, and POP3 work together to ensure your messages are delivered securely and efficiently.

With FastHostCity’s mail hosting, you get:

  • Professional email addresses under your domain (name@yourdomain.com)
  • Reliable servers (mail.yourdomain.com)
  • Full protocol support (SMTP, POP3, IMAP)
  • Secure connections and easy setup

Whether you’re running a business or managing a personal site, understanding these protocols helps you get the most from your email hosting.