I want to send an anonymous email
There are several options for sending an anonymous email. One of which involves a pseudonymous email where any data identifying you or your location is stripped from the message. A level of technical experience is required as you move further down the anonymity scale in your email communications. This is especially true because of the problem posed by email metadata.
You can register a temporary email address (good for one day) to receive an email anonymously from the https://anonbox.net project. You can send an anonymous email using the Paranoici remailer service. It will wrap your email message in several layers of encryption, anonymising the metadata of your message.
The ‘easiest’ way to send an anonymous email (containing no identifying metadata about the conversing parties) is over the Tor Hidden Service network. You can register an email account in Torbox (http://torbox3uiot6wchz.onion/) and access its webmail service from a Tor Browser or through a Torrified Thunderbird client. The recipient must use the same service for conversing with you.