An e-mail alias is an email that uses exactly the same mailbox along with the initial e-mail address. For instance, you could have email@example.com as your authentic address and create an alias firstname.lastname@example.org. The two email addresses will be able to share the very same mailbox, so emails sent to either one of them shall be received in a single place. Feel free to use aliases for several reasons, like emailing various types of people or registering on websites. Any time you start getting a number of spam, for example, you can simply eliminate the alias while your original mailbox won't be changed in the least and you'll keep the e-mails that you need. Aliases are often considered to be a substitute for forwarding emails from one mailbox to another if you use more than one email address for contact on your website.