The Underscore Archives

Matt

well, i will re-read this...

and thankyou for taking the time to write a proper explanation

i was on the right track *speculating* what was going on

but certainly suspected information being written in headers..but I am
certainly the OF THE mere mortal variety you speak of

thanks for your time

chris


On 6/19/07, Matt Hamilton <matth at netsight.co.uk> wrote:
>
> On 19 Jun 2007, at 14:42, Chris Brock wrote:
>
> > Matt,
> > thanks for that
> > I will admit that I know little about this or SPF as you say..
>
>
> SPF in a nutshell is an attempt to stop people's mail addresses being
> abused. As you probably know it is possible to set your 'mail from'
> address to anything you want when you send an email.  And many people
> do this for very legitimate reasons, eg. you might be at home on a
> Virgin Media connection, yet set your email program to say your
> return address is me at myworkaddress.com.  The problem is that anyone
> could do that, and there is very little checking, so I could use your
> email address and go sending spam out.  You then get the replies and
> the rants etc.
>
> SPF attempts to stop this by allowing a domain owner to specify which
> mail servers on the internet are allowed to send mail with that from
> address.  ie I could say that only mail.netsight.co.uk is meant to be
> sending out mail addressed from someone @netsight.co.uk.  Other
> participating mail servers can check this and discard mail not
> complying (this is all optional and not mandatory at all).  the
> problem comes when people start forwarding mail about.  A real world
> scenario of something like this is imagine someone with a hotmail
> address, who has a domain hosted somewhere else and forwards mail
> from this domain to their hotmail account.  Ie mail sent to
> matt at myvanitydomain.com is forwarded to matt at hotmail.com.  If, say,
> my sister also has a hotmail account and sends me some email to
> matt at myvanitydomain.com it will eventually get back to
> hotmail.com.... but... hotmail sees a message *from* a hotmail
> address *to* a hotmail address, but coming from some random server
> called mail.myvanitydomain.com.  It thinks this is fishy and drops it.
>
> That is a bit of a simplification, and to complicate matters more,
> hotmail doesn't actually use SPF, but its own system that is similar
> but not quite the same as SPF.  There are schemes to re-write headers
> so that this can all work, but they are quite complicated and often
> beyond the realms of mere mortals.
>
> -Matt
>
> --
> Matt Hamilton                                       matth at netsight.co.uk
> Netsight Internet Solutions, Ltd.        Business Vision on the Internet
> http://www.netsight.co.uk                             +44 (0)117 9090901
> Web Design | Zope/Plone Development & Consulting | Co-location | Hosting
>
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