POP3 and IMAP are two different protocols (methods) used to access email. If you are using a mail client (thunderbird, outlook, or live mail) or are accessing your email through your phones mail app (android and Iphone) you are using one of the protocols.
POP/POP3
POP downloads email from your server to your device or computer. It leaves a copy on the server and your device has a seperate copy.
- POP never deletes anything on your server
- Your device (phone, tablet or computer) is a replication of what is found on your mailserver
- If you are using two devices, they will both show new mail as read and download a copy. If you read mail on one device, the other will stay show it as unread
POP3 downloads email from a server to your device, then deletes it from the server*. Because your messages get downloaded to a single computer or device and then deleted from the server, it can appear that mail is missing or disappearing from your Inbox if you try to check your mail from a different computer.
*Depending on your settings, outlook for example allows you to disable this setting.
IMAP
IMAP is a direct connection. It syncs all your email across your devices, including your server.
- Email deleted on your device will be deleted on the server
- If you read mail on one device, the other will stay show it as read
- Sent messages will appear on all devices, regardless of what device you sent the email from
Recap
You can use multiple computers and devices to check your email.
Sent mail is stored locally on your PC, not on a mail server.
Unread email shows up on all devices, even if read on another device already.
You can use multiple computers and devices to check your email.
Your mails are stored on the server.
Sent mail stays on the server so you can see it from any device.
Read email is synced across all devices.
