Anti Spam Hints and Tips

Monday, October 09, 2006

Delaying AKA Greylisting vs Spam collecting

Bayesian (spam) filters rely on being able to collect at least some spam emails as well as some good emails. And if you want to keep up with the changing face of spam, you need to be collecting recent spam as well as just looking through the old archived spam from months back.
However, the assorted "trickery" used by ASSP at the network level means a lot of spam is blocked very early on. In particular, the delaying/greylisting seems to stop a lot of spam quite dead, and of course it never collects the spam email itself. It's simply respponding to the initial EHLO command. So you can end up in a situation (like I find myself in) where, although you're blocking 87% of incoming emails as spam, you can never actually collect any of them for the spam database.
I've ended up running for half a day without delaying to boost my database. And turned off delaying for my little group of SpamLovers. A long term solution needs to be found however.
And I'm trying to better exploit the Spamtrap address. The spam trap address I'm using already existed before ASSP. It's the address that belonged to one of our technicians who worked here for a few years and seemed to put his name down for all sorts of crap. He's been gone for a long time now, but still seems to get heaps of junk email. So far, that passive spam-trapping has been all I've needed, but with Delaying, I need to take it further.
I'm going to try posting the address on as many forums, newsgroups and bulletin boards as will let me, and see if the volume increases. Hell, I may even try to "Remove" him from some mailing lists.

Tuesday, October 03, 2006

Happy Bounce messages

OK, so a bit bored and I've rewritten my ASSP bounce messages. This does serve a purpose. It makes it easier to spot my bounce messages, and then track them back to ASSP. As incoming emails can be blocked (in my set-up) by five different filters, it's quite useful to be able to isolate which program has blocked stuff.

Bayes

577 Message Integrity Failure. Spell check (Khoisan:!Kung) Failed. Server Memory Leak, advise top-up immediately. This may be a permanent failure. Message was not delivered. Send error reports to admin @

Relay

530 Replaying Failure. UPS Blocked IRQ packet. UPS Responded with; No routable interface found for that DNS protocol. Please rewind tape to beginning.

Invalid recipient

550 5.1.1 Mailbox . There is no one available to take your mail. If you would like to leave a message for EMAILADDRESS, please send after the beep, and be sure to include you return address. If you have been routed to this incorrectly, please verify address details at http://www.imdb.com/search and retry.

PB Blocking

554 5.7.1 Astropneumatic oscillations in the servers' water-cooling have created too many packet collisions for available packet ambulances. Packets are being routed to /dev/null, but /dev/null is reporting full. Upgrade of /dev/null to handle cavitation in water cooled packet ambulance routing recommended.

Bad Sender

550 5.5.0 EHLO/HELO rejected by server. SMTP 666 Error. Specific server error was " REASON. " Probable failure in CPU alignment or positron focusing. Repack bearings and rotate CPU.

Delay

451 4.7.1 Transient recursive traversal of loopback mount points failed. Please try again later.

RBLs (sbl.spamhaus.org|xbl.spamhaus.org|list.dsbl.org|relays.ordb.org|combined.njabl.org|smtp.dnsbl.sorbs.net|zombie.dnsbl.sorbs.net|nomail.rhsbl.sorbs.net)

471 4.7.1 Delivery NOT Authorized. Please insert $1 coin to continue. Message was refused at this time. Blacklisted by RBLLISTED. This error indicates that the sending IP address (the email server) has been listed as a source of spam. We (Manaccom) cannot remove you from these lists. You (or more accurately your email system administrator) need to contact the listing authority (http://RBLLISTED) for methods to remove the server from the list. XBL or ORDB lists => THIS MAY INDICATE YOUR EMAIL SERVER HAS BEEN EXPLOITED BY SPAMMERS! ACT NOW! XBL lists are listing IP addresses known to be being used to send mail through exploited systems, via virus infections, trojans or other "zombie" methods. OpenRelays (ordb) are mail servers that will forward anyone's mail for them. Spammers use exploited systems and open relays to hide behind other systems when sending their mail.

Bad Attach

575 Microelectronic Riemannian curved-space fault in write-only file system. Part 2 and later of multipart SMTP message failed to authenticate with Cerberus. Homework eaten error. Remainder of message delivered sucessfully to /dev/null.

See? Fun. :-)