SMTP reply codes

[roger-qpsmtpd-list]

        In going over some information about SMTP reply codes, it appears
that certain error codes (numbers) should be used with certain commands
(only, sometimes). Is this correct, or can we issue any error code at any
time?

        For example, the check_spamhelo plugin returns a 550 error if we
received "helo aol.com", even though only the following are supposedly
valid: 250, 500, 501, 504, 521, and 421.

        Should this be considered a problem?

        Thanks.

-- 
Roger Walker
"HIS Pain - OUR Gain"