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The New Type of Spam
07-24-2004, 04:50 PM
Post: #1
The New Type of Spam
Ok so far the beta test is going well (ok one problem but those happen).

The next piece of SPAM I want out of my mailbox is the random word spams in the subject line and a enbedded HTML link that automatically loads and makes your account as active..

This is a pretty difficult piece of spam to tag but as much as I really hate to walk down this path can Amavis do a reverse DNS lookup and see if the IP address the SMTP mail is being sent from = known DNS machine.. That is, SMTP is not being sent from a Dynamic IP assigned address.

I am not really a fan of this kind of filtering but unless someone else knows how to setup a filter this these kinds of messages then this seems the only path one can take..
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07-24-2004, 06:38 PM
Post: #2
The New Type of Spam
Our goal here is not to eliminate 100% of spam to users' inboxes. We have to come to a compromise between customizability and simplicity / speed / efficiency.

In other words, while we'll certainly tweak the SA rulesets if we end up going with this solution (both for speed and for effectiveness), this isn't going to be a solution that will allow you very fine grained control over how your mail is filtered.

We do block certain messages outright, and are likely to do more of this. However we are unlikely to start blocking mail from dynamic / residential space, nor are we likely to make it possible for users to do so.
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07-24-2004, 06:42 PM
Post: #3
The New Type of Spam
Also, note that SpamAssassin *does* add a positive score for messages sent from IPs that are listed as residential - in fact it does this to a fault -- since it has no way of knowing which Received lines are which, it adds a positive score even if a dialup / residential IP is first in the Received chain (which is ridiculous in my opinion, since dialup and Cable / DSL users have to send mail through /somewhere/). I assume that this will be "fixed" at some point.

To get back to what I was saying in the last post; our goal here is to come up with something that will filter *most* spam for most users, and give users some control over if and how their mail is filtered.

By tweaking the score required to tag a message as spam, you may be able to get rid of these messages from your inbox.
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07-24-2004, 09:15 PM
Post: #4
The New Type of Spam
Thanks Will,

I am not a big fan of blocking Dynamic IP address since I run my own SMTP server anyway.

It was just a thought on how it might be possible to tag incoming "spam" from a IP address that does not have a MX record.
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07-25-2004, 01:05 AM
Post: #5
The New Type of Spam
IP addresses don't have MX records.

Do you mean IPs without reverse DNS (i.e., without PTRs)?

That's a totally separate thing from whether an IP is dynamically assigned (or "residential").

If we were going to block such mail, we'd do it at the MTA level... however a lot of spam comes from hosts with valid reverse DNS, and a lot of legitimate mail comes from hosts without same...
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07-25-2004, 01:24 AM
Post: #6
The New Type of Spam
The more I think about it the harder it gets to block this kind of spam..

I think the best way will be to have only one very limited "public" email account and any other accounts setup to allow accept email addresses that are on a whitelist, rejecting anything else..

Lets home DH can find a way to implement this Smile
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