For most users, IMAP is a better choice than POP.
POP is a very old way of receiving mail in an email client. It only lets you download your Inbox on your computer, and not any other folders. When an email is downloaded using POP, it is usually then deleted from Fastmail.
IMAP is the current standard for syncing your emails and lets you see all your Fastmail folders on your email client. You can quickly view subjects and message bodies of emails. IMAP also lets you sync folders between your home computer, your phone, and Fastmail on the web, so that you see the same folders and messages wherever and however you access your email.
Differences at a glance
| IMAP | POP | |
|---|---|---|
| Flexibility | ||
| Delete or move a message without having to download it. | Must download all messages. | |
| Download only the body of a message. | Must download entire message, including attachments. | |
| Synchronisation | View messages in all folders. | Only view messages from the Inbox. |
| Changes made on the web and on your devices stay in sync everywhere. | Once downloaded, changes can only be made on your home computer. | |
| Access messages at home, work, and through the web. | Access messages only from a single device. | |
| Backups | All messages kept with multiple backup copies on Fastmail's servers. | Once downloaded, the message only exists on your local computer. If it crashes, the message is lost. |