Mailing List Archive

Hello

excuse me if it has already been asked ;-)

i've got several mx servers
some of them are backup mx

when the primary mx is "off" (for maintenance reason ...)
the e-mail are sent to the backup mx, and when the primary
mx server is "on", the queued mail are sent from the backup mx
servers to the primary mx server

let's imagine that there is no spf filter on the backup mx
but only on the primary mx server

i wonder if my spf filter will work. i guess not
but ...

another point is ... in this case, it would be a
very good solution to send e-mails through
backup mx if i was a spammer

am i wrong ?

thank you

Yannick
CTO
www.rueducommerce.com




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On Sat, Sep 11, 2004 at 02:54:08AM +0200, Yannick Simon wrote:
> i wonder if my spf filter will work on my primary server
> because the previously queued email are now sent by
> the secondary mx to the primary mx
>
> i guess not

You're right, it won't work. You'll have to whitelist your secondary on
your primary anyway, or else a lot of mail would be rejected due to spf
(since none of the original senders would have included your secondary
in their spf record).

> another point is ... in this case, it would be a
> very good solution to send e-mails through
> backup mx if i was a spammer
>
> am i wrong ?

Again, you are right, and this is what many spammers were already doing
before spf anyway. They assume secondary mx'es are not as well equiped with
anti-spam measures as the primaries are (and usually this is the case).

So you better have a secondary which also does spf-checks and everything
else you do as anti-spam (rejecting bad HELO's etc..)

Koen

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