IMAP and POP are two protocols that mail programs use to access mail stored on remote computers.

How do I know if I normally use IMAP or POP to check my mail?

The vast majority of users access their mail using POP. So if you don't know which you use, you can safely assume it's POP.

What's the difference between IMAP and POP?

IMAP works by keeping mail on the server. POP works by downloading your mail to your computer.

What does this mean to me?

If you usually use POP to check mail, then when you use the Webmail interface you'll only have access to new mail -- none of your folders will be available. Likewise, if you create folders via Webmail and move mail to them, that mail will not be available the next time you check your mail via POP.

Also, IMAP will insert a message into your INBOX to keep track of certain things. This message will only be visible when you check your mail using POP. Despite what the message says, it is safe to delete it.

If you normally use IMAP to check your mail, then all of your folders will be accessible using the Webmail interface.