I am going to patch qmail-smtpd to have a maximum number of rcpt to's
it will accept in one session. (I regularily see spammers that try
to send to a lot of (valid) adresses in one bulk).
The value I am thinking of is around 20 and after that I will reject
the recipients with a "451 Too many recipients." message.
Looking at RFC821 I find (Page 42)
recipients buffer
The maximum total number of recipients that must be
buffered is 100 recipients.
Thus this patch would violate RFC821. Do you think this violation is
critical? A correctly implemented smtp server should resend those
"451 ack'd" addresses anyways, shouldn't it?
Hmmm ... thinking about that quote (maybe it's my bad english) does that
make a sense at all? What's the meaning? Wouldn't
The MINIMUM total number of recipients that must be
buffered is 100 recipients.
make more sense if one would like to impose a limit?
And why (some lines later at that page) would one reject too many
recipients with a "552 Too many recipients.", i.e. a permanent failure
code instead of a 4xx temporary code?
Puzzled,
\Maex