However, you can convey the idea in French using phrases like:
* Lettre de rupture: This literally translates to "breakup letter" and is a general term.
* Lettre de fin de relation: This translates to "letter ending a relationship" and is a more formal option.
* Lettre d'abandon: This translates to "abandonment letter" and is a more dramatic way to express it.
You could also use more specific phrases depending on the context, for example:
* Lettre de rupture amoureuse: For a love break-up.
* Lettre de rupture amicale: For a break-up between friends.
Ultimately, the best way to convey the meaning of "Dear John" in French depends on the specific situation and the desired tone.