How do you say "Thank you for writing" or "Thank you for the letter"?

Question

How do you say "Thank you for writing" or "Thank you for the letter"?

Answer 1

I would also say "gracias por tu (su) carta". "Tu" or "su" depending on the familiarity level with the person.

Answer 2

Gracias por la carta. (Thanks for the letter)

Answer 3

Gracias por contactarme.

Gracias por escribirme.

(The verb infinitive in Spanish often can be used as a noun and often in English would be a gerund or present participle).

Thank you for contacting me.

Thank you for writing to me.