An email alias is an extra address that delivers mail into an existing mailbox — it isn't a separate inbox of its own. Any mail sent to the alias lands in the same mailbox as your main address.
Sending as an alias
When composing a message in webmail or a desktop/mobile mail client, you can choose which of your addresses or aliases appears in the "From" field. You can only pick from addresses that already exist on the mailbox — not arbitrary addresses on your domain.
Creating an alias
See "How Do I Add an Email Alias?" for the steps.
Aliases vs. forwarders
Aliases and forwarders aren't the same thing. A forwarder copies or redirects mail to a different address entirely, while an alias is just another name for the same mailbox. OX App Suite supports several forwarder types separately from aliases.
