I am totally confused. A search on the domain hestersoncoffee.com.au https://whois.auda.org.au/ indicates it is registered by godaddy. GoDaddy offer these settings for workspace accounts https://au.godaddy.com/help/server-and-port-settings-for-workspace-email-6949 What I can not figure out what any of that has to do with outlook or iinet. Did you perhaps opt to pay for office365 as part of the package? In which case you may need to use the owl extension for Thunderbird to connect to the exchange server. But still nothing to do with iinet.