What Is POP3(Post Office Protocol 3)?

Almost everyone uses email in their day-to-day lives. We send emails, receive them, and even trace them via email headers. POP3, or Post Office Protocol 3, is an email protocol used for retrieving messages. It's one of the core ways we exchange email. In this article, understand what POP3 is, how the POP3 protocol works, and how it compares to other email protocols like IMAP.

What is POP3?

POP3, or Post Office Protocol version 3, is a common standard email protocol. POP3 protocol is used for receiving emails. It retrieves email messages from a server over a TCP/IP connection. The current version is the third version of the original protocol, hence the '3' at the end of POP3.

Much like a post office clerk, POP3 receives emails from the sender and holds them on a local machine until users download them. Essentially, Post Office Protocol 3 is a one-way client-server protocol used by web-based email clients to retrieve emails from email servers.

Like other email protocols, such as Internet Message Access Protocol (IMAP) and Simple Mail Transfer Protocol (SMTP), POP3 aids emails in reaching their destinations. Post Office Protocol 3 and Internet Message Access Protocol are both pull protocols, meaning they receive messages rather than push them like SMTP.

But Post Office Protocol 3 was originally designed to only support one-way email synchronization, allowing users to view emails from just one device. This means you can use the protocol on your smartphone or your tablet to retrieve your emails, but you can't access those emails on all devices simultaneously.

However, Post Office Protocol 3 allows users to view emails offline, which is a definite advantage. Users can configure, update, and maintain POP3 protocol with greater ease than with other protocols.

What's the purpose of POP3?

The primary purpose of Post Office Protocol 3 is to provide a simple, standardized way of retrieving emails from a remote server. When a recipient connects to the mail server, POP3 downloads all email messages from the server to the local computer so you can view them offline.

The protocol doesn't store emails on the server, like IMAP. Instead, once the emails download to your computer from the server, Post Office Protocol 3 deletes them. Think of it as a "store-and-forward" service; POP3 retrieves mail, then downloads and deletes it once the recipient gets it.

In general, POP3 aims to make the email delivery process easier as long as the email client settings are correct. The email program of your choice, such as Microsoft Outlook, should be configured to host this protocol; most are automatically designed to work with standard protocols like Post Office Protocol.

How does POP3 work?

Suppose you want to send an email to your colleague. First, the mail travels from your PC to the sender's mail server with the help of the SMTP push protocol. Once sent, the process transfers to POP3 as the pull protocol.

The sent message will stay in the mailbox until the intended recipient downloads it on the local machine via POP3. POP3 is for receiving incoming emails on the web. The POP3 client retrieves email messages from the server to a local device instead. Then, it deletes all data - including messages, folders, and other attachments - from the remote server.

Unlike other protocols, the content isn't synced by default. POP3 protocol only downloads what's in your inbox folder, which is where your messages are. It won't download any other folders or their content, like your sent items, deleted items, or drafts.

With POP3, the receiver is only tied to one device. It's impossible to access the same email from multiple machines simultaneously. However, POP3 has undergone several enhancements in an attempt to address this problem.

Developers have introduced new features to make POP3 a more sophisticated protocol. Because of this, many 'webmail' services these days can configure POP3 in a way that keeps the original copies of files intact for some time. This allows users to download their emails as often as possible within a given time frame.

In general, POP3 is a well-supported mail protocol, but it lacks synchronization. You're likely to lose some important data if your computer fails as no copies of emails are kept on the server.

Features of POP3 protocol

Post Office Protocol is the simplest of all email protocols. Its limited functionality makes it easy to understand, and it's not yet outdated; even though new email protocols have emerged over the years, POP3 is still in use.

The third version of Post Office Protocol is essentially the standard protocol for receiving mail. POP3 pushes emails sent via SMTP to the recipient's mailbox, and, once received, the emails are filtered into appropriate folders and held until download. The protocol is designed to delete emails as soon as they're downloaded, which helps save space and limit data storage. Under some circumstances, an administrator may specify that emails are saved on the server for a certain period of time, but generally, they are eliminated upon being downloaded from the server.

POP3 is popular, simple, and convenient, which makes it useful to email users of all skill level. It guarantees a high success rate provided you configure it the correct way. It's also well-supported; most email programs such as Gmail, Microsoft Outlook, and others are designed to work with Post Office Protocol 3.

POP3 ports

Like IMAP, which uses port 143 and port 993, Post Office Protocol 3 maintains two-port functionality. This means that it works on two ports by default. However, the two differ in terms of encryption.

The default port for POP3 is TCP port 110, which doesn't provide email encryption. This port works for Post Office Protocol, but it doesn't encrypt communication across the channel. Port 995, on the other hand, is the encrypted port for POP3 and works over SSL.

Therefore, POP3 port number 995 is the safer port, since it allows end-to-end encryption and provides confidentiality between sender and recipient. It's used for secure applications for obvious reasons.

Advantages and disadvantages of POP3

Post Office Protocol 3 has been refined since its establishment in 1984. Although developers are still working on improvements to the protocol, as it stands now, here are the advantages and disadvantages of the POP3 protocol.

Advantages

• Downloaded messages are accessible without an Internet connection. Everything is downloaded to your device. An Internet connection is necessary only when downloading emails from the server.
• POP3 saves mailbox space. The protocol frees up server space as it deletes all emails from the server. It's also good at receiving bulk emails.
• It provides fast access to emails addressed to you. All the attachments are already stored on your local machine.
• Settings configuration is simple. The simplicity enables you to retrieve emails with minimal errors.

Disadvantages

• POP3 isn't intended to support email synchronization on the server. It downloads emails to your device and deletes them from the server.
• Emails can only be accessed from a single dedicated device. You can't download emails to multiple devices at once.
• Transferring mail folders from your local PC to another PC is very difficult. The protocol doesn't make this procedure simple, which can be a disadvantage.
• The attachments stored on your PC can become corrupted. You may need to back them up to protect them fully.

Ultimately, we recommend you use POP3 if you want to access your inbox folder offline, if you only use a single device to access your email, if you want to pull bulk email messages to your computer, or if you don't mind organizing your emails into folders.

How to set up POP3 in Gmail

Many people use Gmail as their default email client. Some prefer to use other email clients like Microsoft Outlook or iOS Mail. However, if Gmail is your preferred client, you can configure it to use the POP3 protocol. Here's how to do it in a few steps:

1. Sign in to your Gmail account on your desktop.
2. Click Settings.
3. Click See All Settings.
4. Find Forwarding and POP/IMAP and scroll until you find the POP Download section.
5. Select Enable POP for all mail or Enable POP for all mail that arrives from now on and save your changes.

By doing this, you can access, read, and edit your emails using Post Office Protocol 3.

Frequently asked questions

What's the difference in IMAP vs. POP3?

The difference between the IMAP and POP3 email protocols is the versatility of email retrieval. Both are pull email protocols, but Post Office Protocol was replaced by Internet Message Access Protocol due to the latter's flexibility in email retrieval. IMAP can retrieve emails regardless of location, device, or time; POP3 downloads all new emails from the servers, and users can only read emails from the device on which they download the messages. With POP3, emails only exist on your local device and are deleted from the server.

Should I use POP3 or IMAP?

Both standard protocols are related to email retrieval. Ultimately, as the successor to POP3, IMAP is more modern and generally superior as it allows you to access email on any device. However, Post Office Protocol 3 allows for easier implementation and is also less prone to errors. Both protocols are still integrated into most email clients.

Do I need both IMAP and POP3?

No, you don't need both protocols; they perform the same basic pull function, so users only need one.

What is the default port number for POP3?

Port 110 is the default port for Post Office Protocol 3. However, port number 995 also works with the protocol, providing an encrypted connection for applications that require more security.

Is POP3 incoming or outgoing?

The Post Office Protocol 3 server is an incoming email server, as it retrieves emails.

Does iPhone use POP?

No. Neither Android nor iOS devices support Post Office Protocol 3 email servers.

However, you can configure your Gmail, Outlook, or Yahoo! account to accommodate this feature by signing into your email address, syncing your email to save and import the calendar, and syncing your phone to import your contacts. Then, add that email account to your iOS or Android device.