The best solution to attract the attention of the customers right in their inbox is hidden preheader. This extra space is a perfect way to empower email subject message, explain email essence or inform about sales.
To set it for your email, click the Settings icon and insert the desired text in the Hidden preheader field.
If you only need the email subject without a hidden preheader, please select the Fill in with white space option.
In this case, clients will see your email this way