Making an email alias means setting up an e-mail address which shares the exact same mailbox with a completely different address both for the incoming as well as the outgoing emails. For example, you can create an e-mail address email@example.com and it will be associated with its own mailbox. After that, you can make an alias firstname.lastname@example.org, which can use the mailbox of sales@ and won't have a mailbox of its own. Once you check your emails, you will notice emails sent to either one of the two email addresses in one location, which can be more convenient in some cases because you will not have to sign in and out of different mailboxes using webmail or create various email addresses in an email application. This feature can be used as a substitute for forwarding emails from a single e-mail address to a different one if a number of email addresses are included for contact on a website.