You can customize tons of Eudora settings by using s. They are mostly defined at X-Eudora-Settings.txt. All you do is copy the tag to a new message in Eudora. It will become a link, double click it, and then change the options.
A very useful one is: <7818>. It allows you to change the text when you reply to a message. I use the string: “At ^3 ^1, ^0 wrote:” to show “At time date, person wrote:” and the time, date, and the original sender’s name are placed automatically before the quoted earlier message.7818>
Several years ago, I added in a Eudora setting that reads aloud the “bad” words in incoming messages. Unfortunately, that code is not publicly listed on the eudora web site any more, and I have no idea how to turn it off now. So I have to mute my computer when it starts spewing obscenities.