How to set up IMAP, POP, and SMTP: A complete guide to using your email on any client

When we want to manage our email from an application like Outlook, Thunderbird, or even from our mobile phone, it's essential to understand how protocols like IMAP, POP3, and SMTP work. These three names may seem like unimportant technical acronyms, but they're actually the foundation that allows your messages to arrive correctly, whether you're reading or sending them. And as is often the case, choosing the wrong thing or configuring something incorrectly can result in frustrating errors or even the loss of important emails.

In this article we will explain in a simple but complete way how to configure your email accounts using these protocols, so that you not only understand what IMAP, POP and SMTP are for, but also how to choose the one that best suits your needs and how to configure them correctly, regardless of whether you use Windows, Mac, mobile, or any other device. Get ready, because here we'll tell you everything step by step.

What are IMAP, POP, and SMTP and what are they used for?

Let's start with the basics: these three protocols allow mail programs to communicate with the servers where your messages are located. Although they work differently, they're all necessary for you to check, receive, and send emails from a manager like Outlook, Gmail, Apple Mail, or Thunderbird.

POP3 Protocol: What is it and when to use it?

The POP3 protocol (Post Office Protocol version 3) is designed to download emails from the server to your device. Once downloaded, they are usually deleted from the server, which means that You will only have access to those messages on the device where you downloaded them..

It is useful if:

• You only check your email from one device..
• You want to free up space on the server downloading emails and deleting them from the source.
• You don't need messages to be synchronized between multiple devices.

Of course, if you want to keep a copy on the server, many email clients give you the option to "leave a copy of messages on the server." But if you do this, make sure you don't have multiple devices downloading at the same time, or you could end up with duplicate messages or sync errors.

IMAP Protocol: What is it for and why is it recommended?

IMAP (Internet Message Access Protocol) allows the mail remains on the server and is not permanently downloaded to the device. Instead, a copy is accessed and any changes made (read, archive, delete, etc.) syncs across all devices.

This is ideal when:

• You use multiple devices to check your emails (mobile, computer, tablet…)
• You want to access your mailbox from anywhere, with all the changes updated..
• You need to sync folders like Sent, Drafts, or Files between devices.

The main disadvantage is that takes up more space on the server, but if you have a service with good capacity storage or you can increase your quota, it is undoubtedly the most practical and modern.

SMTP: the outbound bridge for sending emails

SMTP (Simple Mail Transfer Protocol) is a protocol exclusively designed for sending emailsEvery time you click “Send,” your email client uses SMTP to contact the outgoing server and deliver that message to the recipient.

It's important to put attention on:

• SMTP only handles sending, not of reception or storage.
• Requires correct configuration of port, authentication and encryption to ensure that messages are sent without errors.
• If you fail to configure SMTP, you will not be able to send emails, although you can receive them without any problem.

IMAP vs. POP3: Which One Should You Choose?

This depends a lot on how you use email. Here's a quick comparison:

Feature	IMAP	POP3
Storage	On the server	On the local device
Use on multiple devices	Fully synchronized	It doesn't sync
Offline access	Limited Time	Full
Server space required	Greater	Minor
Recommended if…	You use multiple devices and need syncing	You only use one computer and want to save server space.

General IMAP, POP, and SMTP Settings

While the steps may vary slightly depending on your email client and provider, these are the basic settings typically required:

Configure the incoming server (IMAP/POP)

• IMAP server: It's usually something like imap.yourdomain.com or outlook.office365.com
• IMAP port: 143 (without encryption) or 993 (with SSL)
• POP server: something like pop.yourdomain.com or pop.gmail.com
• POP port: 110 (without encryption) or 995 (with SSL)
• Username: your full email address
• Password: that of your email account
• SSL: It is recommended to activate it whenever the provider supports it

Configure the outgoing server (SMTP)

• SMTP server: smtp.yourdomain.com, smtp.office365.com or smtp.gmail.com
• SMTP port: 25, 465 (with SSL) or 587 (with STARTTLS)
• Authentication: Yes, use the same one as for the incoming server
• SSL / TLS: mandatory to avoid blocking by the provider

Specific recommendations by email provider

gmail

In Gmail, it is necessary enable IMAP access from web settings, in the “Forwarding and POP/IMAP” tab. Additionally, it is recommended to use OAuth-compatible clients for added security. Outlook 2019, Apple Mail, and others apps modern ones support it. You can also learn more about how set up Android messaging.

Outlook.com and Microsoft 365

It is common to have to manually enable IMAP permissions on the recent activity page (account.live.com/activity). Additionally, it is recommended to review the server settings from Outlook Web App, where the necessary information for IMAP, POP, and SMTP is located in the advanced settings section. If you need help, follow This tutorial on scheduling email sending in Outlook.

Custom servers (such as IONOS, SiteGround or Active24)

In hosting services, access to email requires that your device is compatible with TLS 1.2 or higher. Many services require ports 993 (IMAP), 995 (POP), and 465 or 587 for SMTP. You must configure security settings correctly and use your full address as your username.

Common mistakes when setting up email and how to fix them

Failed to send emails (SMTP)

• Use a incorrect port (e.g. 25 blocked by the provider).
• Lack authentication enabled SMTP.
• Lack of SSL/TLS certificate or poorly defined security settings.

Emails not syncing (IMAP)

• Outdated or unsupported email client.
• Unstable connection preventing real-time synchronization.
• Too many emails or large folders can slow down the process.

Duplicate or lost emails (POP)

• Enabling “leave a copy on the server” without knowing exactly how it syncs.
• Various configurations with POP on different devices.

How to set up Outlook, Thunderbird, and Apple Mail

Most of these apps allow manual configuration. Just choose "Add Account," select "Manual Configuration or POP/IMAP," then enter the server, port, and authentication information as explained. In Thunderbird, for example, these are detected automatically, but you can customize them if you wish. In Apple Mail, you'll need to manually specify the servers if the wizard fails on the first try. If you need more information, visit our article on How to delete sent emails in Outlook.

Using IMAP, POP3, and SMTP doesn't have to be complicated if you know what you're doing. In this comprehensive guide, we've covered when it's best to choose one protocol over another, how to properly configure ports, security measures like SSL/TLS, and how to address the most common errors in any system or application. By choosing the right configuration, you'll be able to get the most out of your email, regardless of the device or client you use.