En tete mail

You're referring to the French phrase "en tête" which means "in the head" or "at the top".

In the context of email, "en tête" is often used to refer to the subject line or the title of an email. It's a common phrase used in French-speaking countries to ask someone to summarize the main point or topic of an email in the subject line, so that the recipient can quickly understand the purpose of the email.

For example:

• "Pouvez-vous mettre en tête votre réponse pour que je puisse la trouver rapidement?" (Can you put your answer in the subject line so I can find it quickly?)
• "J'ai besoin d'une réponse en tête pour prendre une décision." (I need a response in the subject line so I can make a decision.)

In English, we might use phrases like "Can you summarize the main point in the subject line?" or "Please put the key point in the subject line" to achieve the same effect.