[LINK] RFI: Spam-registration of IP-addresses

Roger Clarke Roger.Clarke at xamax.com.au
Sat Nov 21 07:14:10 AEDT 2020

If anyone can point me to relevant sources to help me understand and
address the following problem, I'd be very appreciative!


It appears that all messages that I've sent to Yahoo addressees, incl.
Rocketmail, at least since early September, have gone into the
recipients' spam-buckets.

In the few copies of messages I've received from relevant
correspondents, there is nothing in the Subject: to indicate Spam.

In the only set of headers I've been able to acquire, I can see nothing
that represents a criterion to cause the email-client to fling it into
the spam-bucket.

The SMTP-server I use has *not* been registered on any spam-servers at
any relevant time.

I've trialled sending via a couple of different SMTP-servers, and that
makes no difference to the behaviour.

I've rebooted the codec, and hence acquired an alternative IP-address
(in a quite different range), but the behaviour remained the same.

The aspect I've investigated as a probable cause is as follows:

Every message carries the originating IP-address as well as that of the
first SMTP-erver.

My IAP, TransACT/iinet, appears to register with Spamhaus the dynamic
IP-addresses that it provides its customers.  (I assume that the reason
is to protect their own spam-reputation, but they've responded slowly,
seldom and uninformatively throughout;  so I don't know that).

An ISP, by registering with Spamhaus the IP-addresses it rents to its
customers makes it impossible to run one's own SMTP server on a
home-LAN.  (I trialled that at one stage a few years back, although, for
me, it turned out to be more trouble than it was worth).

I've never heard of receiving ISPs testing originating IP-address
against Spam databases.

OTOH, some of the messages I've sent from IP-addresses other than that
allocated by iinet have got straight through to the receipient's mailbox
at Yahoo and not to their Spam box.

As I understand it, the purpose of spam-registers is so that ISPs
receiving email can check the IP-address **of the SMTP-server** from
which a message is despatched.  If some threshold volume of messages
from that address is detected as spam, the SMTP-server is registered as
a rogue.  The ISPs that subscribe to that spam-service thereafter
interpret all messages from that SMTP-server as spam, and mark it as
such.  That may result in a warning being inserted into the
Subject-line, markers being inserted into headers which cause the
message to go into recipients' spam-buckets, or (worst of all, when it's
a false positive), simply dropped,

I've been unable to get any action from iinet.  I've also found no way
to get any reaction from Yahoo or Spamhaus.

Any leads or suggested lines of investigation much appreciated!


Roger Clarke                            mailto:Roger.Clarke at xamax.com.au
T: +61 2 6288 6916   http://www.xamax.com.au  http://www.rogerclarke.com

Xamax Consultancy Pty Ltd      78 Sidaway St, Chapman ACT 2611 AUSTRALIA

Visiting Professor in the Faculty of Law            University of N.S.W.
Visiting Professor in Computer Science    Australian National University

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