Sam Varshavchik wrote:
> Bowie Bailey writes:
> > Bowie Bailey wrote:
> > > I have received a request from one of my users to block emails to
> > > their domain from a particular address. Since I don't want to
> > > block the address from the entire server, I think the place to do
> > > it is from maildrop. What I can't figure out is how to direct
> > > maildrop to bounce the message.
> > >
> > > What command can I give to maildrop to make it send a dsn back to
> > > the sender? And can I specify the error message?
> >
> > To answer my own question, I was able to do it like this:
> >
> > LCSENDER=tolower($SENDER)
> > if ( $LCSENDER eq "[EMAIL PROTECTED]" )
> > {
> > echo "This account is not accepting mail from $SENDER"
> > EXITCODE=64
> > exit
> > }
> >
> > I was going to do a recipient rule and put it in
> > /etc/courier/maildroprc, but I decided to put it in the individual
> > user's .mailfilter files instead so that any errors would be
> > limited to that one domain.
> >
> > The rule for maildroprc would have looked like this:
> >
> > LCRECIP=tolower($RECIPIENT)
> > LCSENDER=tolower($SENDER)
> > if ( $LCRECIP =~ /@mydomain\.com/ && $LCSENDER eq
> > "[EMAIL PROTECTED]" ) {
> > echo "This account is not accepting mail from $SENDER"
> > EXITCODE=64
> > exit
> > }
> >
> > Does anyone see any problems with this?
>
> No, that's going to do exactly what you think. The thing is that
> anyone can send an E-mail using anyone's return address, to a
> malicious entity with advance knowledge of this can use you to flood
> this address with bounces.
>
> This is exactly what rcptfilter is designed to do.
Interesting. I wasn't aware of rcptfilter.
The docs are a bit vague on exactly how to use it. It looks like it
uses the maildrop syntax and just produces an exit code. So I can put
the same code from above into .mailfilters/rcptfilter rather than
.mailfilter?
Is there a global version of the rcptfilter, or is it strictly per-user?
As a related question, is my tolower call in the code above necessary or
does courier automatically lowercase the email addresses?
--
Bowie
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