IMAP and POP3
IMAP and POP3 are protocols for retrieving email from a server. IMAP syncs messages and folders across devices; POP3 downloads messages to one device and usually removes them from the server.
The main difference
| Aspect | IMAP | POP3 |
|---|---|---|
| Sync | Yes, across devices | No |
| Storage | On the server | On the device |
| Folders | Supported | Limited |
| Server quota | Important | Smaller |
| Best for | Multiple devices | One device/offline |
Secure ports
| Protocol | Secure port | Older port |
|---|---|---|
| IMAP | 993 (SSL/TLS) | 143 (STARTTLS) |
| POP3 | 995 (SSL/TLS) | 110 (STARTTLS) |
| SMTP | 465/587 | 25 |
Use SSL/TLS. Port 25 is often blocked by ISPs and is not suitable for user email submission.
What to watch for
- Mailbox quota. IMAP keeps messages on the server; a large inbox can fill it.
- Deletion behavior. POP3 can remove messages from the server after download; be careful when switching devices.
- Sent items. IMAP usually syncs the sent folder; POP3 often does not.
- Provider configuration. Hostname, port, and SSL must match the documentation.
- Forwarding is not IMAP. Forwarding redirects messages; it does not sync a mailbox.
- Migration. When moving providers, copy the mailbox over IMAP so folders and read state come along.
For a team opening email on a laptop and a phone, IMAP is almost always the better choice. POP3 is still useful for offline archives or a single device. If the provider limits IMAP connections, reduce active clients or use IDLE sparingly. Enable 2FA and use an app password.
FAQ
Which is safer, IMAP or POP3?
Both can be secure with SSL/TLS. The difference is the sync model, not basic security.
Does POP3 delete email from the server?
It depends on the client setting. Many clients offer “leave a copy on server”; if disabled, messages are removed after download.
Why does email not appear on my phone?
Make sure the account uses IMAP, not POP3, and that the folders to sync are selected. Check the mailbox quota too.
Disclaimer: Hosting Wiki articles are prepared for educational and reference purposes. Hosting technology keeps evolving, so some technical details may change over time.