For all those who want to know what an email is about without having to actually open it, there is the pre-header.
The pre-header is the summary message that appears in text form after the sender name and subject line in an inbox.
While less prominent than either the subject line or sender name, the pre-header can be used to give additional information about the specifics of the marketing email to entice the recipient to open the email, although it is still important to leave things just unclear enough that the recipient might actually want to find out more.
In TEO platform you need to add the preheader in a text widget in the top of the email body.
Add your descriptive text about what you reader can expect and give them even more reasons to open you email.
Change the color of the text to the same as background color of email body. Now you prehader will show in the summary field/preview of the email