On Fri, 11 Jun 2004, Greg A. Woods wrote:
>
> If you reject at RCPT time based on your dislike of the HELO parameter
> then you're only confusing the sender, at best.
There are a number of reasons for rejecting the RCPT command because of
problems with HELO or MAIL FROM, instead of rejecting immediately:
You might apply weaker security restrictions for email to postmaster
in order to make it possible for people to send problem reports via email;
You might want a more complete record of attempts to send email (including
sender and recipient email addresses) to make it easier to diagnose
problems accurately;
The extra data might be useful for passive analysis of host behaviour, to
identify spammers or virus infections etc.
I agree that it could be considered to be confusing, but this can be
mitigated by ensuring that the error messages are useful. Yes, the error
message may be lost by incompetent software, but crapware is capable of
reporting the wrong error even if you speak the protocol as plainly as
possible. A recent example was Outlook reporting the "503 valid RCPT
command must precede DATA" error rather than the RCPT rejection that would
have clued in the user.
--
Tony Finch <dot@???>
http://dotat.at/
