Outlook Calendar in Thunderbird

This has been something of a thorn in many peoples side.  It is simple to press the publish button in an outlook.com account on the web and add the resultant ICS file to Thunderbird as a read only calendar.  But what if you want a calendar you can update, one that syncs both ways.  Until now I had though it was simply not possible.  But it appears I have been mistaken.

So how to do it.  It is in fact fairly simple,  but has a crucial step that has to be executed before you try and set up the calendar.

Click this link. https://outlook.com/ews/exchange.asmx
You will be asked for your password and user names.  These are the same username and password you use to log into the Outlook.com web site.  In my case my Hotmail.com email address and associated password.  Once you are authenticated you will see a web page advising you that your have created a service and giving a lot of instructions about how to create a code file.

Not important in our world.  What we have done is enabled EWS on the URL for ourselves.  Up until this point is you put in the URL https://outlook.com/ews/exchange.asmx into Thunderbird using the ESW add-on it would simply give an error about being forbidden.  Now it just works.

So the next part is easy;

1. Locate the EWS exchange add-on. download link here 
2. Open Thunderbird's  add-on manager by clicking on the on the tool bar and select add-ons
3. Drag the entry for exchangecalendar-v3.8.0.xpi from that page to the Thunderbird add-on manager and drop it.
4. When the install dialog opens (it will take a little while as the add-on is downloaded) click install. 

Or use the instructions here

Once the add-on is installed and you have restarted Thunderbird before configuring a new calendar.

• Open the calendar tab.
• Right click in the calendar list pane
• Select New calendar.
• Select "On the Network" and click next.
• Select Microsoft Exchange 2007/20110/2013 and click next
• Give your calendar a name and select the email associated with the calendar
• Click next 
• Select Hosted Exchange
• Server URL  https://outlook.com/ews/exchange.asmx
• Primary Email address <Your primary outlook email address, no alias>
•  User name  the user name you enter to log into Outlook.com.  For me it is my email address again.

(The following were the default values. I did not change them)

• Domain Name is blank.
• Share folder Id is blank.
• Folder base is "Calendar Folder"
• Path below folder base is /
• Check the server name and settings and complete the Wizard using it's defaults.

I have not yet tested this over a period of time.  But after a number of hours I still have a rad write outlook.com calendar in Thunderbird.

Please  let me know if this does not work.  I have not found it anywhere else on the web, and I doubt my own abilities.  Perhaps it only works for a day.  Only time will really tell.