---
title: "How Email Works: MTA, MDA and MUA Explained"
description: "**In short:** Email has three parts: the MTA (such as Exim) sends and receives messages between servers over SMTP; the MDA (such as Dovecot) delivers the message to the recipient's mailbox and lets you read it over IMAP or POP3;…"
url: "https://www.hyyat.com/en/knowledgebase/how-email-works/"
updated: "2026-09-30"
category: "Add-ons services to host"
---

# How Email Works: MTA, MDA and MUA Explained

**In short:** Email has three parts: the MTA (such as Exim) sends and receives messages between servers over SMTP; the MDA (such as Dovecot) delivers the message to the recipient's mailbox and lets you read it over IMAP or POP3; and the MUA is the email program you use, such as Outlook or webmail. IMAP keeps messages on the server, while POP3 downloads them to one device.

Email service is included with every hosting plan. Here is how it works behind the scenes.

## 1. MTA (Mail Transfer Agent)

The MTA sends and receives email between servers using the SMTP protocol, usually on port 25 between servers (and 465 or 587 when your email program sends through your server). Examples: Exim, Postfix, Sendmail. SMTP defines how mail moves from one host to another and works between servers running different operating systems.

## 2. MDA (Mail Delivery Agent)

The MDA delivers the message to the recipient's mailbox on the server, and lets email programs read it using IMAP or POP3. Example: Dovecot.

### IMAP or POP3?

- **IMAP** (Internet Message Access Protocol) keeps messages on the server, so you can read them from any device, program or webmail. Best for most users and for shared mailboxes.
- **POP3** (Post Office Protocol) downloads messages to one program and usually removes them from the server. Use it only if you read email in one place.

## 3. MUA (Mail User Agent)

The MUA is the program you see and use to read and write email, such as Outlook, Thunderbird, the Mail app on your phone, or webmail.

![How incoming and outgoing mail works](https://www.hyyat.com/wp-content/uploads/2019/01/do-mail-server-configuration-on-linux-servers.jpg)

See also [how to get your email settings for Outlook and mobile](https://www.hyyat.com/en/knowledgebase/email-client-settings-cpanel/).

**Related service:** [Hyyat Host email hosting](https://www.hyyat.com/en/email-hosting/) gives you professional email on your own domain, with 24/7 support.

 **Need this service from Hyyat Host?**Our team handles it for you, with support replying to tickets within 24 hours at most.[Email Hosting](https://www.hyyat.com/en/email-hosting/)[Business Hosting](https://www.hyyat.com/en/business-hosting/)