

The plugins can extend Thunderbird to support synchronizing Calendar and Address Book (Contacts) between Thunderbird and Exchange Online. But Thunderbird has a rick set of plugins through its plugin system to extend its functionalities and there are plugins available to support ActiveSync which is supported by Exchange Online for synchronizing Calendar and Address Books (Contacts).

Although Exchange Online provide IMAP for synchronizing emails, it provides no methods natively supported by Thunderbird. Office 365 provide the cloud version of Exchange named Office 365 Exchange Online. Exchange is a widely used email and calendar/ address book service software. With the Lightning plugin, Thunderbird can support calendar functions well. Thunderbird is a nice email client available on Linux and Windows.
