You can send a test email at any time to see what your customers will see when they receive your emails.
While editing any email or broadcast, you can click Actions > Send test email in the email editor.
This will let you enter the addresses to which you'd like to send a test email. This test email will include dummy data that is automatically generated to review your email layout.
Your shop may be using Jilt's legacy editor, in which case the send test email button will look like this: