Author: Marcin Krol Date: To: exim-users Subject: Re: [exim] Transparently faked domains
Graeme Fowler pisze: >> Could this work? Pros? Cons?
>>
>
> Forwarding services, of which there are literally hundreds of thousands,
> will be broken since the envelope-from will differ from the incoming
> hostname (however you work it out).
> True - but there's exactly the same is a problem with SPF. Yet, SPF gets
deployed.
> Domestic users - millions of them - with their own domain but forced via
> there ISP's outbound mailers for policy reasons (which is after all a
> good thing) will fall foul of it. This category doesn't just cover
> domestic users, it covers people who use email clients at work for their
> own domains bu have to use their employer's outbound SMTP server too.
>
Hm, didn't think of this one, that's a hard cookie.
> Servers with no rDNS or invalid or incorrect rDNS (through no fault of
> the user since the providers are usually in control - allegedly - of the
> PTR zones for their ranges) will fall foul of it.
>
That's actually a good thing - nowadays users of a few mail servers I
manage would not be able to send mail to half of their correspondents if
revdns was lacking there. *something/someone* should get them to clean
up their act, because their mess is where spammers hide.
> If you have a problem with your DNS server, or a network problem makes
> your resolver unable to do lookups to certain parts of the internet,
> you'll start rejecting messages.
>
> It's almost like SPF :)
>
