E-mail aliases allow you to set up an e-mail address at your site's domain that is automatically redirected to an existing e-mail account. This means that an address like firstname.lastname@example.org can be set up, and any mail sent to it will be delivered to another pre-existing address, such as email@example.com.
Setting up an e-mail alias is very simple. Just click on "E-mail Aliases" and enter the alias you want on one side of a row, and the address you want the e-mail to go to on the other side. All changes are instantaneous, so feel free to test your alias as soon as it is created. If you want a single alias to go to more than one address you can enter several destination addresses seperated by commas. However, if you start adding lots of destinations it might be better to make an e-mail list, and store the destination addresses in a database.