You can create anything that looks like an email for testing purposes like fake@nowhere.com the restriction that an email is only used once is long since gone. You can also create your own plus addressing to create multiple test users that all send to you like if my email was Me@mlayten.com I could do Me+Test_User1@mlayten.com and Me+FakeUser2@mlayten.com and they will most often get delivered correctly to Me@mlayten.com , note that some corporate email systems block any mail with plus addressing, so you might need to use a personal test email which should be fine for most purposes.
Also note that by default all email is off by default in non-production environments. The user profile has an option to Receive emails from this test environment in between Email Locale and Notifications in the Edit Person panel.

Same Melinda Layten - Now at Freeman Company as a Workfront System Admin
Living deep in the Northwoods