[Mimedefang] Deadline for SPF records *long w/morbid horoscope*

[Jeff Rife]

On 11 Aug 2004 at 10:38, Cor Bosman wrote:

> > The companies that offer #2 also offer ways for you to retrieve the e-
> > mail with your MUA software, so they don't *want* to deal with passing 
> > it on to an MTA.
> 
> This is not true. Im not sure how many 'most' ISPs you are talking
> about, but I know quite a few ISPs that accept all email for a
> domain and forward to a customer.  This is most prevalent in
> dialup/isdn situations where you basically 'store and forward' all
> email for customers that are mostly offline.  When they come online
> that triggers a queuerun towards the customer.

In many cases, this is handled not by server-to-server, but by a client 
contacting the ISP server and retrieving the e-mail and then sorting it 
out in whatever way.

In any case, this is in reality no different from a client calling up 
and getting the mail from a server.  Because the ISP is the only MX, it 
should know about all the deliverable addresses, simply to avoid 
dictionary e-mailings to these "offline" domains.

> You perhaps confuse ISP with US ISP?

I think I confuse ISP with "quality ISP".

> > So, again, I think it's pretty odd for an ISP to be *the* MX for your 
> > domain but then just pass it along to your server.
> 
> And again, you are wrong :)

Not for "real" domains.  If the ISP is the *only* MX and you retrieve 
your e-mail as if you are a client (not an MTA), then it is the 
responsibility of the MX machine to know what is and is not 
deliverable.

Again, this completely solves the issue of forged return address bounce 
e-mails.


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