Now that your email address has changed, you will need to re-create your profile in Outlook to update the "sender's address". If you do not do this, all your OUTGOING mail will have the old email address.
NOTE: This only affects those who have set up the desktop client. If you exclusively use webmail, this is not a concern.
You will need to do this on EVERY computer you use the desktop client. These changes are specific to the computer, not to your network profile.
Open (File) Explorer or IE (this does not work in Chrome). Go to: T:\Teacher's Utilities\Shortcut to mail profiles.lnk
A window will appear.
Select "Show Profiles".
Select all the profiles and select "Remove".
Now reopen Outlook and set-up your new profile using your new burnabyschools.ca address. (Complete instructions are here: https://bnstech.zendesk.com/hc/en-us/articles/115001433971-Setting-up-Outlook-desktop-client-on-your-PC)