Mailing List Archive

Colin Hirdman wrote:

> If we are sending e-mail campaigns for clients using their
> client lists and want to use their domain name as the from
> header (or from address), are we going to run into problems
> if we're not hosting their domain?

Let's say you use MAIL FROM:<your@smtp.example> and later in
the DATA a From: <your@client.example>

If your sending IP matches the sender policy of smtp.example,
then you get a PASS by a classic SPF check at the recipient.

With a Sender-Id test and a header Sender: <your@smtp.example>
you'd get the same result PASS.

If you don't add a Sender: and the recipient uses Sender-Id,
then he will test the sender policy of client.example, and if
this sender policy doesn't cover your IP you'd get a FAIL.

> Are there any ways around this using SPF?

With SPF classic there's no problem, the From: header isn't
checked, only the MAIL FROM (= Return-Path). With Sender-Id
there could be a problem, and you could get around it if you
add a Sender: <your@smtp.example> matching your MAIL FROM.

But Sender-Id (SPF2.0/PRA) is still discussed, there can't be
any implementations yet, and nobody has a SPF2.0/PRA sender
policy at the moment.
Bye, Frank


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