My university let students put procmail files in their home directories to filter their incoming email. I created a .procmailrc file which set a DISPLAY env var

My university let students put procmail files in their home directories to filter their incoming email. I created a .procmailrc file which set a DISPLAY env variable and then spawned an xterm process. That popped up a terminal on the machine I was sitting at with a shell on the mail server which had write access to every student's home directory.