Thank You Letter After Interview Mail Or Email Do You Think Its Overkill If I Sent An Email And A Letter For A Thank You For Interview?

Do you think its overkill if I sent an email and a letter for a thank you for interview? - thank you letter after interview mail or email

I have a short e-mail informally, an employer perspective, I just had an interview with the 2nd this morning. Now I want to a letter of formal thank you to send in e-mail.

Do you think this is too much? I have an official letter by e-mail after the interview 1st.

Thank you!