POP3 (Post Office Protocol version 3) is a protocol that lets email clients (such as Outlook or Thunderbird) retrieve messages from a remote email server. It is designed especially for offline access: after emails are downloaded, they are usually deleted from the server and kept only on the device.
📬 Key Features of POP3
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One-way communication: emails are downloaded from the server to the device; changes on the server are not reflected on other devices.
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Offline use: once downloaded, emails can be read without an Internet connection.
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Saves server space: messages are deleted after downloading, freeing up space on the server.
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Port number: usually works on port 110; port 995 is used for secure connections with SSL.
🛠️ When Is POP3 Used?
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If email is managed from a single fixed device (for example only from a desktop computer).
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If server space is limited and storing emails locally is preferred.
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If Internet access is limited, because POP3 is well suited to working offline.
🔄 POP3 vs. IMAP Comparison
| Feature | POP3 | IMAP |
|---|---|---|
| Access type | From a single device | From multiple devices |
| Synchronization | No | Yes |
| Data on the server | Usually deleted | Stays on the server |
| Offline access | Yes | Yes |
| Port number | 110 / 995 (SSL) | 143 / 993 (SSL) |
