Thank You After Interview Email Or Mail Is It Inappropriate To Email A Thank You Letter After An Interview Or Should I Send It Through The Mail?

Is it inappropriate to email a thank you letter after an interview or should I send it through the mail? - thank you after interview email or mail

I had an interview with a reputable company yesterday, and I write the hiring manager a letter of thanks, I'm not sure if it do unwanted e-mail to the hiring manager of the letter or should I be normal and send it by mail ?