Re: I hate to interrupt all this for something practical, but.... we nee

On Oct 31, 2004, at 21:53, Scott Kitterman wrote:
> It's more complex than this perhaps.  Generally, the name that the ISP 
> gives
> you actually resolves to multiple machines with different names/IP
> adrresses.  For example, when I send mail via my domain hosts server, I
> "send" mail to relay.pair.com.  This is actually 5 SMTP servers.
> Fortunately, Pair.com publishes an SPF record for relay.pair.com, so 
> your
> solution works fine.
>
> My cable modem provider is Comcast.  They publish no SPF record at 
> all, so
> I'l left to guess.  So, through trial and error I've come up with a,
> hopefully, comprehensive list of IP addresses:
>
> ?ip4:204.127.202.0/24 ?ip4:204.127.198.0/24 ?ip4:216.148.227.0/24
> ?ip4:63.240.76.0/24
>
> I also have DSL as a backup (I work out of the house, so redundancy is
> critical)).  For that, I use Megapathdsl.net.  They publish an SPF 
> record,
> but it's a bit complex, so the best bet is to include it in my record:
>
> ?include:megapathdsl.net
>
> Additionally, all these are shared MTAs or IP blocks not under my 
> control
> that do not have strong technical measures in place to prevent
> cross-customer forgery (this is true of almost all mail services 
> today), so
> I always put a ? in front of the mechanism so that it gives a NEUTRAL 
> rather
> than PASS result.  This is important, because I don't want other 
> customers
> of my providers to be able to forge my mail from address.
>
> Also, you will almost certainly want MX in your record to support 
> bounce
> authentication even if people don't send mail from the MX.
Judging from the comments over the last few days, I would change the 
record to:
        IN      TXT     "v=spf1 ?include:ISP.net ?a:ISP.net 
ip4:192.0.2.2 -all"
Of course, since Anne has not responded to this list or to me 
privately, this may be a totally moot discussion.
Andrew
____________________________________
Andrew W. Donoho
awd(_at_)DDG(_dot_)com, PGP Key ID: 0x81D0F250
+1 (512) 453-6652 (o), +1 (512) 750-7596 (m)


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