IMAP vs POP: What’s the difference?

We’ve talked about how email works and how email protocols facilitate the transfer of your emails along the way, from when you hit send to when your subscriber reads your email message. But before we dive into the differences between IMAP vs. POP email, we’ll do a quick refresher on email protocols.

There are three types of email protocols:

• Simple Mail Transfer Protocol (SMTP)
• Internet Message Access Protocol (IMAP)
• Post Office Protocol (POP)

SMTP handles the delivery of messages. In other words, after you hit “send” in your email account the SMTP protocol transfers your message from your email client to your email service provider’s (ESP’s) sending mail server, like Mailgun’s SMTP server. The SMTP protocol continues to carry your message to your subscriber’s inbox service provider’s (ISP’s) receiving mail server and waits there until your subscriber reads your email.

If SMTP handles the delivery, POP and IMAP handle the retrieval of your email message from your subscriber’s mail server to their email client. When your subscriber fires up their email account, their email client, like Gmail, Yahoo, Microsoft Outlook, or AOL, will use POP or IMAP to download messages from the receiving mail server to their email client. The email client can be web-based, like Gmail.com, or app-based, like Microsoft Outlook.

POP (or POP3 to use its latest version) is an email protocol that email clients use to retrieve emails from a mail server. It uses an Internet Protocol (IP) to provide an email client access to a mailbox on a mail server. Then, POP downloads messages from the server to a single computer.

How does POP3 work?:

1. Connects an email client to an email server
2. Retrieves all messages from the email server
3. Stores the messages on the client’s local device or email client
4. Deletes the original message from the mail server

This is the default behavior. Sometimes, POP setups allow you to configure the protocol to leave a copy of the original message on the mail server.

IMAP is a much more sophisticated protocol designed to address the shortcomings of POP. It supports many essential features for modern email usage, such as leaving messages on the server and accessing messages from multiple devices.

How does IMAP work?:

1. Connects an email client to an email server
2. Retrieves all messages from the email server
3. Stores the messages on the client’s local device or email client
4. Keeps the original message on the mail server

Both POP and IMAP protocols retrieve messages from your recipient’s ISP’s mail server.

Both POP and IMAP protocols retrieve emails from a mail server, but they do this differently. IMAP synchronizes emails across multiple devices, allowing users to access their messages from anywhere, while POP downloads emails to a single device and deletes them from the server by default. This makes IMAP more suitable for users who need flexibility and accessibility, whereas POP is a simpler, more lightweight option for users who prefer to store their emails locally.

Some advantages of POP3 are that it:

• Backward compatible with servers that don’t support IMAP
• Easy to implement across most major email clients
• Lightweight and straightforward to use
• Saves server space since old messages are deleted by default

Some disadvantages of POP3 are that it:

• Doesn’t support encryption. This makes POP3 less secure than IMAP
• Can only be used to download messages from a server. This makes POP3 less flexible than IMAP
• Can be slow since it downloads all messages from the server each time
• Can take up a lot of local storage space since POP3 stores all messages locally

Some advantages of IMAP are that it:

• Allows you to keep your emails on the server so that you can access them from multiple devices, including your computer, mobile devices, and tablet
• Allows you to access your emails offline
• Facilitates searching for specific emails on your mail server
• Organizes your emails into folders
• Provides a secure way to access your email because your messages are stored on the mail server and not on your device

Some disadvantages of IMAP are that it:

• Can be slow because it synchronizes the local mail client with the server, which can take some time depending on the size of the mailbox and the speed of the connection. IMAP generally uses more data than POP, contributing to slower speeds.
• Can be unreliable because it is a complex protocol that relies on several different technologies working together. Additionally, IMAP requires more storage space on the email server than POP, leading to problems if the server needs more space.
• Can use a lot of data because it constantly synchronizes the email server with the client, meaning that new emails, deleted emails, and any changes to existing emails are all downloaded to the client. This can use a significant amount of data, especially if there’s a large volume of emails.
• Can be challenging to set up because it requires more complex server settings than POP.
• Isn’t supported by all ESPs, which can make it difficult to use all of the features of the protocol

IMAP supports all the essential features for modern email usage. But there are some situations where POP may be the better choice. Should you use POP vs. IMAP in Outlook? Let’s take a look at when you should use each protocol.

When should I use POP over IMAP?

• When your subscriber’s receiving mail server doesn’t support IMAP
• When you only access email from a single device
• When your internet connection isn’t consistent
• When you have limited server storage

When should I use IMAP over POP?

• When you need to access your email from multiple devices
• When you need to store a copy of the original email on the mail server
• When your ESP supports IMAP
• When your local storage is limited
• When you usually have a good internet connection

We’d recommend IMAP over POP in most scenarios, IMAP supports remote access for multiple clients managing a single inbox. And long after its creation, this still aligns with how we need to use email.

We hope we’ve answered your questions on IMAP vs. POP but if you want to learn more about protocols, how to improve your workflow, and other niche email topics, don’t forget to subscribe to our newsletter.

Author: The Sinch Mailgun team The Sinch Mailgun team shares news, best practices, and strategies to take your products and apps to the next level using email. Subscribe to our newsletter to get all the articles in your inbox!