An alias or an email alias to be specific is an email with the primary purpose of forwarding emails to other email addresses. The terms email alias is the same as Email Forwarding For example, firstname.lastname@example.org to email@example.com, so that you only have one inbox to check. You can have many email aliases to forward emails to one or multiple email accounts. Email forwarders offer a number of benefits. First, you can set up a generic company email address, such as firstname.lastname@example.org for inquiries and have those inquiries routed through to the relevant person or team within your organisation. Second, you can chose to route emails to application of your choice such as Gmail, Office 365 etc. However, you cannot be able to send emails with an alias address any reply will show your primary email address as the sender.
Click here to learn how to setup an alias.