Before sending an email you'll want to make sure it looks right. This is where you use the Preview Tab.

Go to: Email > Preview and view the email.

The tab contains 2 sections.

Email Preview

The Preview section allows you to view the HTML / Source / Text versions of your content with all the tokens and rulesets rendered to display as your recipients will see them.

It is also possible to start your testing in this section by using the following:

Send Test – Send the current content for the specific Recipient as a test to an email address of your choice.
Create Email Preview – Send the current content for the specific Recipient to Litmus to check how that exact version renders across a wide variety of email clients.

Data Preview

On the right side the Data Preview allows selecting and filtering of the attached data in order to view specific versions of the content.

Using the filters you can choose to see only recipients who have matching values in their Profile fields. Add/Remove Fields using the Profile Fields button in the toolbar and combine filters to view just the Recipients you want.