What is POP3?

September 8, 2024

POP3 (Post Office Protocol version 3) is an email protocol used to retrieve emails from a remote mail server to a local email client (like Outlook, Thunderbird, or Apple Mail). Once the emails are downloaded from the server, they are typically deleted from the server, although there are options to keep copies on the server.

Key Features of POP3:

  1. Email Retrieval:
    • Post Office Protocol 3 is designed to download emails from the server to your device, allowing you to read them offline. Once downloaded, the emails are typically stored locally on your computer or device.
  2. Limited Synchronization:
    • It is not designed for synchronization between devices. If you check your email on multiple devices (e.g., phone, laptop, desktop), the emails will only be available on the device that downloads them. The changes made (like reading, deleting, or organizing emails) on one device are not reflected on others.
  3. Email Deletion:
    • By default, after emails are downloaded, they are deleted from the server. However, most email clients allow users to change this setting and leave a copy on the server for a specified period or indefinitely.
  4. Offline Access:
    • Once emails are downloaded, you can access them even without an internet connection. This makes Post Office Protocol useful in scenarios where internet access is intermittent or unavailable.

POP3 vs. IMAP:

  • POP3: Primarily designed for offline access, it downloads emails and often deletes them from the server after retrieval.
  • IMAP (Internet Message Access Protocol): Designed for accessing emails across multiple devices. Emails are stored on the server, and changes made on one device (like marking as read or deleting) are reflected across all devices.

POP3 Workflow:

  1. Your email client connects to the POP3 server.
  2. The email client downloads new emails from the server.
  3. The emails are stored locally on the device.
  4. Emails are optionally deleted from the server after being downloaded.

Post Office Protocol 3 Ports:

  • Port 110: Standard port for non-encrypted Post Office Protocol 3 connections.
  • Port 995: Used for connections secured with SSL/TLS encryption.

When to Use Post Office Protocol 3:

  • Limited server storage: If your email provider offers limited server storage, Post Office Protocol 3 can help by downloading emails and removing them from the server.
  • Single-device usage: If you access email primarily from one device, Post Office Protocol 3 can be a simple solution for retrieving and storing emails locally.

Advantages and Disadvantages of POP3

1. Access some of your email without an internet connection

You can read any of your already-downloaded emails on your device without needing to connect to the internet. This is great news for people who need to work or access their email history, regardless of where they are or how reliable their internet connection may be. 

After all, they’re already downloaded to your device. You don’t need to access the server to view those emails because they’ve already been deleted from the server anyway.

2. You will need far less server space

As emails are automatically deleted from the server, your server space never gets cluttered or overwhelmed by a huge backlog of email data. Even though it may be inconvenient at times to store all of your emails on your device, you do get the benefit of a reduced need for server space. 

Overall, while Post Office Protocol 3 is a straightforward and useful protocol for certain use cases, many modern email users prefer IMAP because of its ability to sync across multiple devices.