Email Protocols: POP3, IMAP, and SMTP
Email uses three main protocols for sending and receiving messages, following is the port numbers:
Overview of Email Ports
| Protocol | Secure (Recommended) | Non-Secure |
|---|---|---|
| SMTP | 465 | 25 |
| POP3 | 995 | 110 |
| IMAP4 | 993 | 143 |
For users traveling abroad
If you’re traveling overseas and using hotel or mobile networks, please be aware that some service providers may restrict or block certain ports on their networks. This could impact access to email services if your email application relies on specific ports that are blocked.
What to Do if You Experience Issues
If you encounter issues with your email app, we recommend switching to webmail, which operates through a standard web browser and is less likely to be affected by port restrictions. This should allow uninterrupted access to your email.
1. SMTP (Simple Mail Transfer Protocol)
- Function: Sends emails.
- Ports: Usually uses port 25, 587, or 465 (secure).
- Explanation: This is the "outgoing" protocol, responsible for moving messages from one email server to another.
2. POP3 (Post Office Protocol 3)
- Function: Downloads and deletes emails from the server.
- Ports: Typically uses port 110 or 995 (secure).
- Explanation: Great for offline access, but removes emails from the server by default.
3. IMAP (Internet Message Access Protocol)
- Function: Syncs emails across devices, keeping them on the server.
- Ports: Normally uses port 143 or 993 (secure).
- Explanation: Ideal for accessing email from multiple devices without deleting them from the server.