This is a list (not exaustive, pull requests welcome) of the domain names used for mock phishing tests. It is of mine, and a few other people in the space that these types of tests are not something that fixes anything, they may be useful to find who to educate, but that is not really an issue to test this way.
Get better security controls in place. Dont vilify your employees.
This list can simply be added to Outlook or Google Workspaces email block list, that way you will know that the emails you get are either actually phishing attempts, or are some test of your whits.
Outlook: Home > Junk > Junk Email Options > Blocked Senders List > Import from File