To get Thunderbird working with UVic's Exchange calendar you need to have a version of Thunderbird that incorporates the fix for sending passwords in the clear - this means at least v43. There is a version 44 beta out right now that works quite well, so I went through the process of documenting how I got things going. This also works with v45, which was just made available on the PPA.

Install

1. Add the PPA and install/upgrade in the usual apt-get way.
2. download Lightning plugin - note Thunderbird version requirements for each version
3. download the Ericsson exchangecalendar plugin - currently v3.6-beta1

Email account settings
Account settings->Server settings
Server name: mail.uvic.ca, port 993
Connection security: SSL/TLS
Authentication method: Normal password
Outgoing server (smtp): mail.uvic.ca, port 465
Outgoing server connection security: SSL/TLS
Outgoing server authentication method: Normal password

Configure calendar

1. Click the 'Switch to the calendar tab' button (top-right) to view your local calendar (called 'Home').
2. Add new calendar by right-clicking below your 'Home' calendar, and choose 'New Calendar'. Select 'On the network' for location.
3. Select 'Microsoft Exchange 2007/2010/2013' for format, then name the calendar.
4. Check the 'Hosted Exchange' option, not the 'Office 365' option.
5. Check 'Use Exchange's autodiscovery function. Fill in Username (Netlink ID) and Domain (UVIC). Click 'Perform autodiscovery'. You should be challenged for a password.
6. If you got this far you'll be asked to choose an EWS server. I only got one to choose from: https://mail.uvic.ca/ews/exchange.asmx

We have a shared calendar for vacations and so forth. To share a calendar, log in to the account that owns the calendar (through OWS) and right-click the calendar you want to share, and choose 'Share calendar'. In the dialogue that appears, add the email address of the person you want to share with (note that this can only be a UVic email address). It will send an email to this person that has an XML attachment. They can create a new calendar based on the information included in this attachment.

Add shared calendar

1. The email that the share recipient gets has an XML file attached (called 'shared_metadata.xml'). It contains two things we need: SmtpAddress, which is the email address of the person that shared the calendar; and FolderId, which is a very long string (hex?). These are XML elements, and we only need the text values, nothing else.
2. Add a new calendar as above, but in the 'Primary email address' field, use the email address of the person that shared the calendar - not yours.
3. Use your Netlink ID in the 'Username' field.
4. In the 'Share folder Id' field, add the hex value of the FolderId element (from the shared_metadata.xml file).

That should be it. I've had no trouble with this setup, other than being unable to see nested folders - but this problem has been there for ages. For example, I have a folder for the Humanist list that I've placed inside a 'Lists' parent folder. Thunderbird shows me the Lists folder, but not the Humanist folder. This is true for all folders more than one layer deep.