alex at ergens
Mar 23, 2008, 6:35 AM
Post #4 of 4
(429 views)
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On Sat, Mar 22, 2008 at 10:48:26AM -0600, Technical Support wrote:
> I get a lot of garbage mail that is using addresses on our mail
> server as the “Mail From” address. I know that we have not sent these
> messages and I believe that SPF will help to reduce the amount of stuff
> coming to us that says it was sent by us.. So my question is if I enable SPF
> checking will it validate whether the mail came from us and reject and how
> does this impact mail sent to me by others who don’t publish an SPF record?
> Would it be better during the switch to us a either or situation ..
> Pass/Fail; or would a Soft Fail be the best solution?
You don't need SPF for such tests on your own server. You know the
rules, you don't need to communicate them elsewhere (which is what
SPF is about!) If you know ${server_in_china} should not be sending
mail using your name, you do not need SPF to communicate this to yourself.
When transfering a message between two SMTP servers, two distinct roles
exist. You need to separate the two roles. There's a sender and a receiver.
${sender} claims to talk on behalf of ${user}@${domain}
${receiver} uses SPF to fetch the policy at ${domain}
${receiver} judges wether he should accept the message (or similar)
In your scenario, you would be both ${receiver} and ${domain}, so yuo
would be fetching your own policy. This is certainly possible although
perhaps a bit wasting resources.
OTOH you don't need to make an exception for domains you own, which
can be a good thing outweighing the extra use of resources.
As with any email: if ${domain} doesn't publish a policy, or if
${receiver} doesn't use it, SPF won't work (by design). That's why
everybody should implement both sides of SPF, do not just publish
a policy, also enable inbound verification on your servers.
HTH
Alex
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