c tcp_connect localhost:1025

c <~ 220
c -> HELO localhost
c <~ 250
c -> MAIL LALA: <>
c <- 500 5.5.2 Unknown command

c -> MAIL FROM:
c <~ 500

# Reconnect to avoid getting rejected due to too many errors.
c close
c tcp_connect localhost:1025
c <~ 220
c -> HELO localhost
c <~ 250

c -> MAIL FROM:<pepe>
c <~ 501

c -> MAIL FROM:<a@xn--->
c <- 501 5.1.8 Malformed sender domain (IDNA conversion failed)

# Reconnect to avoid getting rejected due to too many errors.
c close
c tcp_connect localhost:1025
c <~ 220
c -> HELO localhost
c <~ 250

c -> MAIL FROM:<aaaa5aaaaXaaaa5aaaaXaaaa5aaaaXaaaa5aaaaXaaaa5aaaaXaaaa5aaaaXaaaa5aaaaXaaaa5aaaaXaaaa5aaaaXaaaa5aaaaXaaaa5aaaaXaaaa5aaaaXaaaa5aaaaXaaaa5aaaaXaaaa5aaaaX@bbbb5bbbbXbbbb5bbbbXbbbb5bbbbXbbbb5bbbbXbbbb5bbbbXbbbb5bbbbXbbbb5bbbbXbbbb5bbbbXbbbb5bbbbXbbbb5bbbbXbbbb5bbbbXbbbb5bbbbXbbbb5bbbbXbbbb5bbbbXbbbb5bbbbX>
c <- 501 5.1.7 Sender address too long