[kwlug-disc] About spamming techniques [was: Nextcloud 11]

[Bob Jonkman]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Chamunks writes
> most of the big email providers will reject those [invalid
> attempts]

And that's the problem. A server which strictly accepts only mail that
passes DKIM and SPF (and DMARC) checks will not let any spam through,
but at the expense of false positives (unwanted rejections) from those
mail servers that don't implement DKIM or SPF.

I see that SPF has finally graduated to "Standards Track" from
"Experimental", but none of these protocols are required for
conformance to the mail standards of RFC5321
https://tools.ietf.org/html/rfc5321#section-3.6.2

- --Bob, who wonders why RFC5321 isn't part of STD10



On 2016-12-15 12:13 AM, Chamunks wrote:
> @Bob I find that for the most part what I've read is that as long
> as you use DKIM and SPF records you can basically prevent spoofing.
> There still will be a few people that try but most of the big email
> providers will reject those from what I read.
> 
> On Wed, Dec 14, 2016 at 9:06 PM Hubert Chathi <hubert at uhoreg.ca>
> wrote:
> 
>> On Wed, 14 Dec 2016 15:30:16 -0500, Bob Jonkman
>> <bjonkman at sobac.com> said:
>> 
>>> Jason wrote:
>>>> If [a spammer] get a notification for blocked messages,
>>>> [spammer] can iterate parameters until you figure out the
>>>> exact configuration.
>> 
>>> Even worse, it causes spam backscatter. If a spammer spoofs
>>> your email address as sender, then when my mail server sends
>>> back a delivery failure message it'll go to you. It's a clever
>>> way for spammers to get their mail to you via my spam rejection
>>> rules.
>> 
>> Yes, that's why it's better to reject mail at SMTP-time, rather
>> than to accept mail and then generate a bounce email.  That way,
>> it's the sender's server who generates the bounce email, and
>> presumably they know the actual sender.
>> 
>> Allowing servers to send mail on behalf of other people is quite
>> a handy feature of email (it allows, for example, email lists and
>> forwarders), but causes spam problems.
>> 
>> 
>> _______________________________________________ kwlug-disc
>> mailing list kwlug-disc at kwlug.org 
>> http://kwlug.org/mailman/listinfo/kwlug-disc_kwlug.org
>> 
>> 
> 
> 
> 
> _______________________________________________ kwlug-disc mailing
> list kwlug-disc at kwlug.org 
> http://kwlug.org/mailman/listinfo/kwlug-disc_kwlug.org
> 

- -- 


- --
Bob Jonkman <bjonkman at sobac.com>          Phone: +1-519-635-9413
SOBAC Microcomputer Services             http://sobac.com/sobac/
Software   ---   Office & Business Automation   ---   Consulting
GnuPG Fngrprnt:04F7 742B 8F54 C40A E115 26C2 B912 89B0 D2CC E5EA



-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2
Comment: Ensure confidentiality, authenticity, non-repudiability

iEYEARECAAYFAlhSYOwACgkQuRKJsNLM5eoUowCgrJrRJDCMGSgXFUMS+UgiaZhl
L24AnAiIUKTI4ADdEKbGtiekKPaG2iws
=NxtS
-----END PGP SIGNATURE-----