alex at ergens
Mar 26, 2008, 12:52 AM
Post #5 of 5
(912 views)
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On Tue, Mar 25, 2008 at 05:49:36PM -0500, Steve Yates wrote:
A good answer, which could use some expansion:
> > I used the wizard and it generated the following SPF record:
>
> The wizard is an OK starting point but not perfect.
>
> > v=spf1 ip4:192.168.1.0/24 a mx a:no mx:ampawn.com include:no ~all
>
> Breaking down (I assume this is for the domain ampawn.com):
[...]
>
> a
> mx
> - this says the host "ampawn.com" and the MX for ampawn.com can
> send mail.
Looking at A and MX for ampawn, I see:
;; QUESTION SECTION:
;ampawn.com. IN A
;; ANSWER SECTION:
ampawn.com. 21600 IN A 65.198.165.27
;; QUESTION SECTION:
;ampawn.com. IN MX
;; ANSWER SECTION:
ampawn.com. 21600 IN MX 10 mail.ampawn.com.
ampawn.com. 21600 IN MX 100 mail.uu.net.
;; ADDITIONAL SECTION:
mail.ampawn.com. 21600 IN A 65.198.165.27
mail.uu.net will not be sending mail in your name. You don't need
to list it, and perhaps you don't even want to list it. This means
you should change "mx" into "a:mail.ampawn.com".
And then you notice "mail.ampawn.com" has the same address as
"ampawn.com", you can read in the FAQ that each host needs to
be listed only once, so either remove "a:mail.ampawn.com" or
remove "a". We like short, so we choose "a" to stay.
And then there's always the question: "is this a static address?"
to which the answer is often "yes". In such a case, why should a
gazillion receivers lookup the address a gazillion times, if the
publisher of the SPF record only needs to do this once?
Meaning: don't use "a", use "ip4:65.198.165.27".
What remains is: "v=spf1 ip4:65.198.165.27 ~all"
(I know, this was already posted, I just wanted to elaborate on "why")
Make sure to change "~all" into "-all" when you're done testing.
Alex
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