Mailing List Archive: SPF: Help

Survey: When does SPF cause legitimate email to be rejected?

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wayne at schlitt

Aug 6, 2005, 11:28 AM

Post #1 of 5 (901 views)
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Survey: When does SPF cause legitimate email to be rejected?

A question for those who have spent a lot of time helping point solve
problems with SPF failures.

What are the most common failure cases for SPF? (Please indicate
which is the most common.)

For example:

* Legitimate email being rejected due to forwarding.

* Legitimate email being rejected due to being sent from the wrong
location. (aka the traveling mailman problem, or the roaming/home
user problem.)

* Legitimate email being rejected due to mailing lists not rewriting
the MAIL FROM address

* Legitimate email being rejected due to SPF records not containing
all IP addresses that they should

* Legitimate email being rejected due to SPF records having syntax
errors.

* Legitimate email being rejected due to SPF records being used for
PRA checking instead of MAIL FROM checking, or similar cases where
the SPF record is not being used as intended.

* Other cases

While it is fairly easy to detect when SPF is rejecting email, it is
much harder to distinguish between legitimate emails being rejected,
and when some spammer has forged email and the rejection is exactly
what we want.

Looking through the SPF-Help RT reports, it looks like the roaming
user problem is actually roaming user problem is the most frequent,
but I haven't studied the reports closely enough to be sure.

-wayne

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spf at gbesco

Aug 8, 2005, 8:43 AM

Post #2 of 5 (865 views)
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Re: SPAM [In reply to]

wayne wrote:

>* Legitimate email being rejected due to being sent from the wrong
> location. (aka the traveling mailman problem, or the roaming/home
> user problem.)
>
Yep most common here.

---------------------
Well folks,

It has been interesting studying this SPF technology with you
all. But, now it appears this e-mail address is corrupted, and I have
started getting SPAM on this account. Therefore, I must withdraw this
account to keep my network SPAM free. (You will not longer need to hear
my rants.)
Goodbye SPF Help crew, and good luck with your technology.

Nathan Tyler

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steve at teamITS

Aug 8, 2005, 3:11 PM

Post #3 of 5 (858 views)
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Re: Survey: When does SPF cause legitimate email to be rejected? [In reply to]

On Sat, 06 Aug 2005 13:28:42 -0500
wayne <wayne[at]schlitt.net> wrote:

> * Legitimate email being rejected due to being sent from the wrong
> location. (aka the traveling mailman problem, or the roaming/home
> user problem.)

> * Legitimate email being rejected due to SPF records not containing
> all IP addresses that they should

Arguably, the first problem is the same as the second...

> * Legitimate email being rejected due to SPF records having syntax
> errors.

Is this possible? I thought SPF checkers would just stop
processing if a syntax error was reached.

- Steve Yates
- ITS, Inc.
- Sometimes I lie awake at night and ask, "Where have I gone wrong?" Then a voice says to me, "This is going to take more than one night..."

~ Taglines by Taglinator 4 - www.srtware.com ~

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wayne at schlitt

Aug 8, 2005, 4:02 PM

Post #4 of 5 (859 views)
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Re: Survey: When does SPF cause legitimate email to be rejected? [In reply to]

In <20050808170706.FC51.STEVE[at]teamITS.com> Steve Yates <steve[at]teamITS.com> writes:

> On Sat, 06 Aug 2005 13:28:42 -0500
> wayne <wayne[at]schlitt.net> wrote:
>
>> * Legitimate email being rejected due to SPF records having syntax
>> errors.
>
> Is this possible? I thought SPF checkers would just stop
> processing if a syntax error was reached.

Mail admins can decide to do all sorts of things, including rejecting
email due to syntax errors in the SPF record (PermError), rejecting on
SoftFail, rejecting on Neutral, rejecting on None and anything else.

Their servers, their rules.

Rejecting on PermError has a strong following. I'm not one of them
though.

-wayne

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spflist at nospam

Aug 9, 2005, 1:47 AM

Post #5 of 5 (866 views)
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Re: Survey: When does SPF cause legitimate email to be rejected? [In reply to]

On Mon, 2005-08-08 at 18:02 -0500, wayne wrote:
> In <20050808170706.FC51.STEVE[at]teamITS.com> Steve Yates <steve[at]teamITS.com> writes:
>
> > On Sat, 06 Aug 2005 13:28:42 -0500
> > wayne <wayne[at]schlitt.net> wrote:
> >
> >> * Legitimate email being rejected due to SPF records having syntax
> >> errors.
> >
> > Is this possible? I thought SPF checkers would just stop
> > processing if a syntax error was reached.
>
> Mail admins can decide to do all sorts of things, including rejecting
> email due to syntax errors in the SPF record (PermError), rejecting on
> SoftFail, rejecting on Neutral, rejecting on None and anything else.
>
> Their servers, their rules.
>
> Rejecting on PermError has a strong following. I'm not one of them
> though.
>

Since I'm new to SPF I'm not actually rejecting any thing yet. Though
once I'm sure I have my receiving end set up correctly I will most
likely drop SPF fail at the connection and save on Bandwidth. :-)

Surely if someone chooses to provide an SPF record it's up to them to
make sure that it fully describes the hosts they send from. My SPF
record says '-all' so if you don't get a 'pass' then its bogus and
should be rejected. If I'm stupid enough to send mail from a host not
on my SPF list and it doesn't get though thats my fault.

Tom.
--
There are 10 types of people in the world.
Those that understand Binary and those that don't.

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