I will write to him/her
I will write to her tomorrow.
Si él no escribe, yo no le escribiré más.
If he doesn't write, I won't write to him anymore.
Yo le escribiré en cuanto sepa su dirección.
I will write to you as soon as I know your address.
Le escribiré a Tom.
I'll write to Tom.
Le escribiré una respuesta amable.
I will write you a polite reply.
Nunca le escribiré una carta a Mary.
I will never write a letter to Mary.
Le escribiré una carta a Judy.
I'll write a letter to Judy.