When I tried to introduce and implement Action Mailer in the application under construction, I was addicted to the swamp at the beginning, so I will record it as a memorandum.
I got an error when I tried to send 4 emails from the above article
NameError: uninitialized constant InquiryMailer
At first I thought it was a simple error in the class name or file name, but it didn't work at all.
I arrived at the following article, and it seems that spring is doing something wrong. I tried to stop it and it worked.
spring stop