Helpful Guides
Finding the owner of a domain
To find the owner of a domain name (except if the domain ends in Dot AU) use the ICANN Lookup detailed info should show the registrar who can be contacted to gain control of the domain name.
Dot AU domains are managed by the AUDA and can be looked up here WHOIS
To find who manages the email service we can use mxtoolbox.com this will identify the service owner however if it is not Microsoft or Google further investigation will be required.
Services, these are Web Hosting and Email Hosting and are not necessarily managed by the same provider e.g. web may be Wix, Squarespace or private hosting using a WordPress site or similar, email is normally Google Workspace or Microsoft 365 can be older systems that use POP or IMAP hosted on a private server