14 Jul
2012
14 Jul
'12
2:15 p.m.
So, I receive mail that would be killed by SPF checks and I'm thinking
of getting my exim server to use SPF because of this.
So, to the VPS users, I was wondering if anyone who has implemented SPF
checks found downsides to it?
And to the Bitfolk admins, have you considered adding SPF checks to the
Bitfolk SA?
n
14 Jul
14 Jul
2:21 p.m.
Hi,
So, I receive mail that would be killed by SPF checks
and I'm thinking
of getting my exim server to use SPF because of this.
So, to the VPS users, I was wondering if anyone who has implemented SPF
checks found downsides to it?
And to the Bitfolk admins, have you considered adding SPF checks to the
Bitfolk SA?
The Bitfolk Spam Assassin already scores for SPF.
I occasionally see "SPF_PASS" in X-Spam-Status and
"* -0.0 SPF_PASS SPF: sender matches SPF record" in X-Spam-Report.
Regards,
@ndy
--
andyjpb(a)ashurst.eu.org
http://www.ashurst.eu.org/
0x7EBA75FF
3:20 p.m.
On 14/07/12 15:21, Andy Bennett wrote:
Hi,
Ah, yes, I was looking at emails that had gotten through to me that were
clearly spam, they must have been ones that did not get scored because
of SA being unavailable to exim at the time.
I see Received-SPF on some my mail.
I also see X-Spam_score, X-Spam_score_int and X-Spam_bar on, I think,
all of my mail.
I rarely see X-Spam-Status at all.
It would be good to know which headers BF SA is configured to clear and
set so I know which ones I can rely on if SA has run over a message. I
will probably look at clearing any headers I may inspect in exim before
sending it through to SA just in case though.
Thanks,
n
So, I receive mail that would be killed by SPF
checks and I'm thinking
of getting my exim server to use SPF because of this.
So, to the VPS users, I was wondering if anyone who has implemented SPF
checks found downsides to it?
And to the Bitfolk admins, have you considered adding SPF checks to the
Bitfolk SA?
The Bitfolk Spam Assassin already scores for SPF.
I occasionally see "SPF_PASS" in X-Spam-Status and
"* -0.0 SPF_PASS SPF: sender matches SPF record" in X-Spam-Report. 
6:31 p.m.
On 14/07/2012 15:15, Nigel Rantor wrote:
So, I receive mail that would be killed by SPF checks and I'm thinking
of getting my exim server to use SPF because of this.
So, to the VPS users, I was wondering if anyone who has implemented
SPF checks found downsides to it?
An initial disclaimer: I firewall port 22 by country of origin, so
pretty much all email originating from address blocks allocated to
China, Russia, and a couple of others are blocked. Inbound connections
attempting to send spam are therefore reduced by an unmeasured amount.
I've been using SPF for a couple of years now, and haven't experienced
many problems. As an SPF check generally returns one of three states
(pass, fail, neutral), my approach is:
* Accept the email if SPF passes (no greylisting, message then goes
through SpamAssassion etc)
* Reject the email if SPF fails
* Greylist the sender if SPF returns neutral
This has the following benefits:
* Email from senders with correctly-configured SPF records is received
straight away without delays from greylisting
* Email from non-permitted senders is considered spam and is denied on
receipt, so doesn't waste any more time/resources going through the rest
of the system
* Email from senders without SPF records can still be received (via
greylisting)
Then there are the drawbacks:
* Email from senders without SPF records is delayed by the
greylisting. This can be irritating when e.g. signing up to a website
and waiting for a confirmation email.
* Spam originating from hosts which pass SPF checks bypasses greylisting.
* A genuine email which outright fails an SPF check is lost without my
knowledge.
In practice, these drawbacks are fairly minor. A quick scan through my
inbox would seem to suggest that many reputable and competent senders of
email are publishing SPF records these days, and the occassions when
genuine email which I'm interested in reading straight away getting held
up in greylisting are increasingly rare. I've never knowingly had any
problems with genuine email being shot down by an SPF fail.
The worst drawback is the spam originating from senders which pass SPF
checks. This tends to be down to either badly configured SPF records on
the part of originating domains (a straw poll from my spam folder has
turned up several domains with SPF records ending in '+all' ), or
spammers operating from compromised hosts. Such spam tends to turn up in
short bursts and then subside pretty quickly, is low in volume overall
(23 spams from the last two weeks in my deleted folder), and generally
gets hosed by SpamAssassin in any case.
Overall I'm happy with the way it works; my spam volumes are pretty low,
and the drawbacks fairly minor from my perspective.
Also of interest is http://spf-all.com/ which lets you look up the
published SPF record for any domain, and has some fun stats.
--
Phil Stewart
11:10 p.m.
On 14 Jul 2012, at 19:31, Phil Stewart <phil.stewart(a)lichp.co.uk> wrote:
On 14/07/2012 15:15, Nigel Rantor wrote:
25 or 22?
So, I receive mail that would be killed by SPF checks and I'm thinking of getting my
exim server to use SPF because of this.
So, to the VPS users, I was wondering if anyone who has implemented SPF checks found
downsides to it?
An initial disclaimer: I firewall port 22 by country of origin, so pretty much all email
originating from address blocks allocated to China, Russia, and a couple of others are
blocked
15 Jul
15 Jul
9:11 a.m.
On 15/07/2012 00:10, Alex Smith wrote:
On 14 Jul 2012, at 19:31, Phil Stewart <phil.stewart(a)lichp.co.uk> wrote:
Ooops! Yes, I do mean port 25. Port 22 is of course somewhat more
heavily locked down ;-)
--
Phil
An initial disclaimer: I firewall port 22 by
country of origin, so pretty much all email originating from address blocks allocated to
China, Russia, and a couple of others are blocked
25 or 22?
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5 comments
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participants (4)
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Nigel Rantor -
Phil Stewart