Why are my responses to a staff member's email being returned to me as 'undeliverable'?
If you are attempting to respond to a staff member's email using 'Reply' or 'Reply All', and your response is returned to you as 'undeliverable', it is likely you are trying to respond to an email sent prior to all staff being provisioned with an Office 365 for Business account in December 2014.
To send your response please clear the staff member's name from the To or CC field of the message, re-select the staff member from your contact list, then re-send your response.
The reason this may occur is prior to December 2014 only UniSA students had Office 365 accounts (student email is managed by Office 365), so "interim" staff contact records were created to enable students to select staff members from their email contacts. These "interim" staff contact records have now been disabled in Office 365 as they are no longer required (staff now have "legitimate" contact records in Office 365).
If you attempt to respond to a message sent prior to staff receiving Office 365 you will be attempting to send a response to the staff member's "interim" contact record (which has been disabled). You need to delete the staff member's old "interim" contact record then select their new "legitimate" contact record from your email contact list.