IMAP or POP3: What Is the Difference
IMAP synchronizes a mailbox between the server and every device: a message read on a phone is marked as read in webmail and in the desktop client too. POP3 pulls messages to a single device and, by default, deletes them from the server — a second client will never see those messages.
For a mailbox checked from a phone, a laptop, and a web interface at the same time, only IMAP fits. POP3 makes sense in a rare case: one client, one computer, a wish to keep a full archive locally, and to free up quota on the server.
Server Settings and Ports
| Protocol | Port | Encryption |
|---|---|---|
| IMAP | 143 | None or STARTTLS |
| IMAP SSL | 993 | SSL/TLS from the moment of connection |
| POP3 | 110 | None or STARTTLS |
| POP3 SSL | 995 | SSL/TLS from the moment of connection |
| SMTP | 587 | STARTTLS (outgoing mail) |
| SMTP SSL | 465 | SSL/TLS from the moment of connection |
Use the SSL ports (993, 995, 465) wherever the client supports them: the connection is encrypted right away instead of after a STARTTLS command, which lowers the risk of a password being intercepted on unstable networks.
Where to Get the Exact Connection Details
In cPanel, open "Email Accounts", find the mailbox you need, and click "Connect Devices". That page lists the incoming and outgoing mail server name, the login (the full mailbox address), and both ports — nothing needs to be worked out manually. If the mailbox does not exist yet, create it first through setting up mail in cPanel.
The server name is usually mail.example.com or the domain itself — cPanel shows the current value tied to your server.
Setting Up a Client: the General Steps
The steps are the same for Outlook, Thunderbird, and mail apps on a phone:
- Add a new account and choose the IMAP type (or POP3, only if you need it deliberately).
- Enter the full mailbox address as the login, not just the part before the at sign.
- Enter the incoming mail server and port 993 with SSL/TLS enabled.
- Enter the outgoing mail server and port 587 or 465 with SMTP authentication enabled.
- Save the settings and send a test message to yourself.
If the client has a separate "Require authentication for SMTP" flag, turn it on: without it the server will reject sending a message with a 553 or 535 code.
Common Connection Errors
- The login is set to a short nickname instead of the full mailbox address — the server returns an authorization error.
- Port 110 or 143 without SSL is chosen where the network provider blocks unencrypted connections.
- Authentication is not enabled for outgoing mail — incoming messages arrive, but outgoing ones sit stuck in the queue.
- The client shows a certificate warning — use the server name from "Connect Devices" instead of your own domain if the warning gets in the way.
If the client's messages land in spam at the recipient's end, the mail client is usually not the cause: check the domain's SPF and DKIM records and the SpamAssassin threshold on the receiving side.
Summary: a Mail Client Setup Checklist
- Choose IMAP if the mailbox is read from several devices, POP3 only in rare cases.
- Take the ports and server name from the "Connect Devices" page in cPanel, not from memory.
- Use the SSL ports: 993 for incoming, 465 or 587 for outgoing mail.
- Always enter the full mailbox address as the login.
- Enable SMTP authentication — without it, messages will not go out.