document calendar sync for Thunderbird with O365

user-guide/thunderbird_for_o365.md

@@ -1,5 +1,9 @@
 # Configure Thunderbird for 0ffice365
 
+This guide shows you how to access e-mail, address book and calendar with Thunderbird.
+
+**Note**: Microsoft currently has a [problem with IMAP and IPv6](https://answers.microsoft.com/en-us/outlook_com/forum/all/thunderbird-imap-responded-user-is-authenticated/062a82f6-e678-4462-88b7-dd6cc318386f?page=3). Inside the PSI network IPv6 is not available, but from home it might be.
+
 ## Account and MFA ready?
 Before connecting to Thunderbird to Office365, you need to have your MFA token/app configured.
 
@@ -154,7 +158,73 @@ you need to enter your Windos/AD password and then it will also search the PSI w
 
 ## Calendar Integration
 
-TODO
+The calendar can be synchronized using the [TbSync](https://github.com/jobisoft/TbSync) add-on.
 
 
+![Open Add-on Manager](thunderbird_for_o365/thunderbird60_open_addons.png)
+
+Open the hamburger menu at the top left and select "Add-ons and Themes".
+
+![Search tbsync in Add-on Manager](thunderbird_for_o365/thunderbird61_search_tbsync.png)
+
+In the Add-on Manager search in the top left search box for `tbsync`.
+
+![Install tbsync in Add-on Manager](thunderbird_for_o365/thunderbird62_select_tbsync.png)
+
+In the result list below click on the button "+ Add to Thunderbird" for the "TBSync" result line.
+
+![Install tbsync in Add-on Manager](thunderbird_for_o365/thunderbird63_install_tbsync.png)
+
+Now click on "Add"
+
+![Installed tbsync in Add-on Manager](thunderbird_for_o365/thunderbird64_installed_tbsync.png)
+
+and "OK.
+
+![Installed tbsync in Add-on Manager](thunderbird_for_o365/thunderbird65_select_eas.png)
+
+Next we also need the connector to O365, so please also look for the "Provider for Exchange ActiveSync" and click on that line again the button "+ Add to Thunderbird".
+
+![Install Provider for Exchange ActiveSync in Add-on Manager](thunderbird_for_o365/thunderbird66_install_eas.png)
+
+Here again click on "Add"
+
+![Install Provider for Exchange ActiveSync in Add-on Manager](thunderbird_for_o365/thunderbird67_installed_eas.png)
+
+and "OK".
+
+![Open TbSync](thunderbird_for_o365/thunderbird68_open_tbsync.png)
+
+To configure TbSync click onto "TbSync: Idle" on very right in the footer of the Thunderbird window.
+
+![Add Exchange ActiveSync](thunderbird_for_o365/thunderbird69_add_exchange_activesync_account.png)
+
+To add a new account, open the dropdown "Account actions" at the bottom left. Therein select "Add new account" and "Exchange ActiveSync".
+
+![Enter information for Exchange ActiveSync account](thunderbird_for_o365/thunderbird70_add_o365_account.png)
+
+In this dialog select "Microsoft Office 365", then at "Account name" add suitable name for the calendar, followed by the respective email address in the field "User name (email address)". Finish with clicking onto "Add account".
+
+![Authenticate at O365](thunderbird_for_o365/thunderbird71_o365_oauth.png)
+
+Now authenticate with Microsoft.
+
+![Enable O365 calendar sync](thunderbird_for_o365/thunderbird72_activate_o365_calendar_sync.png)
+
+Now with the account set up enable the checkbox "Enable and synchronize this account".
+
+![Configure O365 calendar sync](thunderbird_for_o365/thunderbird73_configure_o365_calendar_sync.png)
+
+In the now newly shown configuration pane select the parts you want to synchronize (probably "Calendar", maybe also "Contacts".
+Further below set the "Periodic synchronization (in minutes)" to a value like `10` to allow for automatic synchronization.
+Now start manually a synchronization by pressing the "Synchronize Now" button.
+
+![O365 calendar sync done](thunderbird_for_o365/thunderbird74_o365_calendar_sync_done.png)
+
+Now all "Status" should be "OK". Close the "TbSync account manager" dialog.
+
+
+![O365 calendar sync done](thunderbird_for_o365/thunderbird75_open_calendar.png)
+
+Finally you can enjoy your calendar.