SMTP 500 Line too long

[Ivar Lumi]

Hi,
After fast look on RFC 5321, i don't see exact place what describes how 
to handle "500 Line too long".

Must server junk bytes(if max line exceeded) and try to read CRLF, after 
that returns "500 Line too long".
or
Must server send "500 Line too long" straight away.

Thanks.