Milter-greylist

fredrik.pettai@... wrote:
 > 
 > > I don't know: what real MTA will change the case between two delivery
 > > attempts of the same message? In what situation did you experienced the
 > > situation above?
 > 
 > I don't think those entries are for the same mail. I think those are
 > different mails but sent to the same rcpt, from the same user, but with
 > different (case sensitive) addresses to the rcpt. (For instance, one
 > message may be a reply on a sent mail from the rcpt, and the other may
 > be written manually by the user.)

Unfortunately, it isn't that simple.  According to RFC2822,
only the domain part is case-insensitive.  So the addresses
bugs@... and bugs@... must be assumed to be
identical (does milter-greylist do that?).  However, the
local part (i.e. to the left of the "@" sign) is interpreted
locally, and it is undefined whether that is case-sensitive
or not.

So, in theory, that means that tom@..., Tom@... and
TOM@... could be the same person, but it is also very
possible that it is three different persons.

Well, it might be possible to add a configuration switch to
milter-greylist so the admin can tell it whether local
domains use case-sensitive mail names or not.  But there is
no way it can know that for remote domains.  If in doubt,
mail names should always be assumed to be case-sensitive,
which is the current behaviour.

A similar issue arises when aliases come into play.  For
example, assume someone sends mail to root@..., and
then also sends a mail to admin@... or webmaster@ or
postmaster@ (happens quite often).  _All_ of those mails
will be greylisted and delayed, even if they are all
aliased to the same person (milter-greylist has no way
to know that).  I think that the behaviour makes sense
and is not a bug.

Best regards
   Oliver

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