spf-discuss
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Re: Mechanism usage in live SPF records

2004-01-27 15:23:04
Will Senn wrote:

wechsler,

and to top it all off, I implemented correctly (i think):
v=spf1 a/25 ptr mx/25 -all

that look reasonable for the low 128 servers?

My brain has passed the point of the night at which I can manage CIDR maths, but that's a valid record.

However I suspect (if all the servers in question are in the same subnet as your MX server) that simply:

v=spf1 mx/25 ?all

would be your best bet. Servers included by one rule do not need to be re-specified by another, and I assume that a/25 and mx/25 have identical meainging in your network.

Only if there are hosts in yourdomain.com do you need the ptr rule as well.

If all your outgoing servers are also listed as mx servers you don't need the /25 either.

?all will protect you against transitional risks documented at:
http://spfwiki.infinitepenguins.net/pmwiki.php/SenderPermittedFrom/FixingForwarding

        Wechsler

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