c tcp_connect localhost:1025

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

c -> MAIL FROM:
c <~ 500

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

c -> MAIL FROM:<a@xn--->
c <- 501 malformed address (IDNA conversion failed)

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