Author: Alan J. Flavell Date: To: Exim users list Subject: [Exim] MTA presents bad HELO but won't take 'no' for an answer
We're seeing occasional examples where we reject the presented HELO
for containing invalid characters. But the sender simply treats it
as a temporary error and keeps re-trying later.
Well, to be exact, they first present EHLO, get it rejected, present
HELO, get that rejected too, and temporarily go away; but they're back
every 10-15 minutes or so to try again.
Is there a convenient way (exim4) to note at the HELO stage that the
presented HELO was bad, but defer giving them the bad news until the
RCPT TO stage? For such pathological cases, this would seem to me to
offer a better prospect of getting rid of them.
As a kludge, one could excuse such misbehaving sites from the HELO
check and block them with an IP rejection, but this needs manual
attention each time that such a situation arises.
