Envelope icon next to file name
I get a monthly usage csv file from my solar monitoring company. I just noticed that some of the files have an envelope icon to the right of the file name. Some don't. Other than the numbers in the files they are identical. What does the envelope icon signify and why do some files have it and some don't? I am running macOS 14.4.1.
Thank you
Mac mini, macOS 14.4