The best alternatives to Fake Mail Generator are MailDrop, InboxKitten, and Email Monster. If these 3 options don't work for you, we've listed a few more alternatives below.
Sign up with your real email and choose a USERNAME. Any email sent to anything (_____@USERNAME.eml.monster) will be forwarded to your real email address. Turn off any alias or sender or both.
Tempbox is an open-source Mac app for disposable emails powered by mail.tm (A free temp mail service). Create disposable emails with the address of your choice (provided not taken already) or with a random address. Archive the address for later use.