How to leave the sysop feedback:

At any menu, you may hit 'f' to leave the sysop e-mail.  Note that this
invokes 'elm' the default mailer on the sysop.  The elm mailer will then
ask for a subject.  It will have 'feedback' as the subject.  You may change
this by backspacing over the subject and entering your own.  At this point,
the editor will be invoked and you will be able to enter your message.
Enter your message, save the message, then exit the editor.  At that point,
the elm mailer will ask you 'Do you want to send this message?'.  You may
enter 'n' if you have changed your mind.  Otherwise, hit 'y' and the
message will be sent to the SysOp.