For example, a Thunderbird user with a Microsoft Live account can use both the Thunderbird application that is installed on their system and the web-based interface provided by Microsoft. Therefore, messages can be stored both on the local machine and on the server, enabling numerous benefits: The IMAP protocol supports both online and offline activity. To see whether your account uses IMAP or POP, check the Server Settings page in the Account Settings: It is more modern and fully featured than POP (Post Office Protocol), which is the other major protocol for accessing mail messages. It enables a mail client (such as Thunderbird) to access messages stored on a mail server.
IMAP stands for the Internet Message Access Protocol. 6 Configuring synchronization and disk space usage.
