What are IMAP and POP3?
IMAP (Internet Message Access Protocol) and POP3 (Post Office Protocol version 3) are protocols that let email clients (like Outlook, Thunderbird or Apple Mail) connect to a mail server to receive messages.
Both serve the same basic purpose —bringing emails from the server to your device— but they work in different ways, with important implications for how your mail is managed.
POP3
- Downloads emails from the server to the device and, by default, deletes them from the server once downloaded (some clients let you keep a copy).
- Mail is stored locally on your device.
- Pros: saves server space and works offline once downloaded. Fine if you only use one device.
- Cons: no sync across devices (each downloads its own copy); if you lose the device you may lose your mail; read/unread status and folders aren't reflected elsewhere.
IMAP
- Keeps emails on the server and synchronizes them with your devices.
- Every change (read, delete, move to a folder) is reflected in real time on all devices.
- Pros: full sync across computer, tablet and phone; your mail stays safe on the server even if a device is lost; shared folders across devices.
- Cons: uses more server space (watch your quota), needs a connection for the full history, and can be slower with very large inboxes.
Side by side
| IMAP | POP3 | |
|---|---|---|
| Email location | Server | Device |
| Sync across devices | Yes | No |
| Server storage used | High | Low |
| Offline access | Limited | Yes (downloaded mail) |
| Backup safety | Always on server | Risk of loss if deleted |
| Best for | Multiple devices | A single device, low quota |
Which should you choose?
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