A simple " thank you" let the sender know that their email has arrived safely, that it has not been lost among what could be 50 other emails that have arrived in your email inbox that day.
On the next line, you need to write your full name and then you need to write your telephone number and your email address on separate lines after your name.
Phone numbers, email addresses, where people live, people's names, all of this information really a treasure trove for cyber criminals who might want to engage an identity theft.