Email Domain
An email domain describes the sections of an email address that follow the @ symbol.
Email domains can be classed as generic (i.e. @gmail.com or @yahoo.com) or custom.
It is preferred that businesses use custom email domains to boost brand recognition and so that any email communication looks genuine in front of customers.
When selecting a custom email domain it's also important to think about the email domain extension such as .co.uk or .com.
Example
An email domain used by customers on your mailing list (B2C) will probably use a generic email domain such as mybusinessname@gmail.com.
As a business, a custom email domain would use both a custom prefix which comes before the @ symbol, as well as a custom domain following the @ symbol.
For example: hello@mybusinessname.com
For more instructions on setting up your email domain and DNS records, please see our tutorial here.