A Mailbox is an email account with an address that has your domain name.
For example, if your domain name is mydomain.com, a Mailbox using that domain name could be you@mydomain.com or sales@mydomain.com.
Why do you need one?
Your own personalized email makes a great professional impression on potential customers and makes it easier to contact you. Wix offers several custom Mailbox options - check them out below.
Source WIX