Here is a collection of the best free email services that allow you to send emails anonymously. While some ask for personal information during registration, this is usually only to help you recover your account if you forget your password.
Top 5 Anonymous Email Providers | NordVPN
GuerillaMail offers a free, disposable, self-destructing, temporary email address. No personal information is required. Use it once or until you see spam, then delete the account. If you are using an Android mobile device, download the app.
5yMail includes an ad at the bottom of each email and allows you to send to only one recipient at a time. If you want to reply to your email or attach files to emails sent to multiple users, upgrade to 5yMail's paid service.
Anonymouse allows you to send an email without having to enter any personal information. That doesn't mean you can send anything, so be aware of the legal implications before sending an email that may not be legal.