Download the Relay extension for Firefox. Select the icon that appears on your Firefox toolbar to access the sign-in page. Sign in with your Firefox account to get started.
As you browse, the Relay icon will appear in form fields where sites ask for your email address. Select it to generate a new, random address that ends in @relay.firefox.com. Relay will forward messages to the primary email address associated with your account.
Sign in to the Relay website to keep track of the aliases you’ve created. If you find that one receives spam or unwanted messages, you can block all messages or even delete the alias, right from the management page.