An email alias is an e-mail that shares a mailbox with a totally different email. For example, you could have email@example.com and also firstname.lastname@example.org and e-mails sent to either one of them will be received in one mailbox. This option will make it much easier and much more convenient to handle various e-mail addresses because you will have to log into just one mailbox if you use webmail or create one single e-mail address in an e-mail application on your desktop. If you create an alias, not only will you be able to get messages, but you will also be able to send emails from the various addresses and they will share the Outbox, so you'll have all communication in one location. Using aliases can be a replacement for working with different mailboxes for different purposes or forwarding a single e mail address to a different one in order to manage the emails of both in a single place.