Re: spam avoidance (was Re: cpu speed problem)

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On Mon, 2007-07-30 at 11:25 +0100, Andy Green wrote:
> I found this to be really effective for over a year now:
>  - greylisting (I use gps + sqlite)

I'm not enamoured of greylisting, though that might be down to the poor
implementations of it that've held my mail up for hours, rather than
greylisting in itself.

>  - Spamhaus RBL lookup (IPs that are detected by Spamhaus as sending
> spam to their fake emails get blacklisted here)

Do they get false positives added by malicious people?  One of my hosts
uses a RBL system, but I don't think it's spamhaus.

>  - tight rules on postfix:
>     - insist that the server has reverse DNS

Not all do, nor do they really have to, even if it's a damn good idea.
This could be a problem.

>     - insist that the recipient user actually exists (end of most
> virus mails)

Does it also reject if the message has more than one recipient, and
they're not all real users?

I put a bait address into a HTML comment on my website, anything that
spammed that (along with any other address) got trashed.  No real user
would have seen the bait, but HTML trawlers would.  I could kill that
mail with 100% certainty.

[tim@bigblack ~]$ uname -ipr i686 i386

Using FC 4, 5, 6 & 7, plus CentOS 5.  Today, it's FC7.

Don't send private replies to my address, the mailbox is ignored.
I read messages from the public lists.

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