Hi Takayuki Miyoshi,
Thank you. I have solved the mystery of the missing messages.
Following the instructions at the link you gave me, I went to my Wordpress dashboard and clicked on Contact > Contact Form 1 Edit, scrolled down to the Mail section, altered the variables, et voila.
It is a testimony to the quality of your plugin that I was able to troubleshoot the problem with minimal instructions. And I'm a writer (not a developer) who has never used Wordpress!
I installed Contact Form 7 based on the recommendation in a popular Youtube video by Tyler Moore on how to create a website with Wordpress.
Regards,
Elizabeth