According to Alan J. Flavell,
> On Sun, 27 Nov 2005, Tony Godshall (replying to me):
> 
> > > I'd recommend blocking patterns of dynamic/generic IP addresses at 
> > > RCPT time, such as this adsl-63-195-120-242.dsl.snfc21.pacbell.net 
> > > (wildcards or regexes can be useful, also there are dnsRBLs that you 
> > > can use).  Then you won't need to get as far as verifying their 
> > > envelope sender domain.
> > 
> > Oh, that one *is* a problem.  I have a static ip myself, but
> > it's dhcp-configured by my cable company, quite likely in
> > the middle of a dynamic block.  People who follow advice
> > like like yours are blocking legit people like me.  Like
> > freakin Verizon does.
> 
> Well, I'm sorry, but your categorisation of "legit" is unfortunate: 
> the truth is that you're going to find increasing numbers of potential 
> recipients who will refuse mail on that basis, no matter how "legit" 
> you consider yourself to be.
...

> For a free-er exchange of mail, you should be using a reliable 
> smarthost (assuming that you are unable to get your own IP address 
> "properly" registered to the satisfaction of the mail admin 
> community).  That's just the way that things are - irrespective of 
> what I might think or say personally about the matter.
...

Well, it is in DNS and it does have SPF records.  I guess I'll 
go dig up the specifics to your vague recommendation if it 
becomes a problem beyond just the one ISP.  Thanks for the
pointer, though.

It's just a form of social darwinism, I guess.  I know of at
least two Verizon customers who have moved their e-mail off 
the Verizon servers because of overly agressive blocking.
It's a good thing for Verizon for now (reduces their mail
load by a tiny tiny fraction) but it also means these people
now have more mobility- they can change ISP without having
to change e-mail addresses again.  ISPs who block to
agressively will lose customers and those who accept too
much will also lose customers.  It's a tricky balance, I'm
sure.

T


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