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Using the Razor Spam Filter
Note: Razor is no longer supported, and has been replaced with our Junk Filter feature!

All DreamHost accounts have Razor spam filtering capabilities!

Razor is a spam filter that uses a continuously-updated centralized database of known spam to decide whether or not incoming mail is spam.

To add Razor spam filtering to a mailbox, just go to our "Mail > Filters and Spam" section and choose a mailbox. Then check off the box next to "Filter spam with Razor", and click "Change Spam Settings"!

Within about an hour the spam filter will be set up on that mailbox.

There are two different ways to set up our Razor filter, depending if you use POP3 to check your email or IMAP/Webmail.


Our server will just add the header X-Razor: SPAM to messages matched as spam. It will then leave the message in your INBOX. This is so that you can then set your POP3 email client on your computer to do what you'd like with your spam. We have to do it like this since POP3 only reads the INBOX off the mail server.


There are three server mail folders you set up when turning on Razor for IMAP or webmail:

  1. Filter Spam To: this is the folder Razor will put messages it decides are spam, as opposed to your Inbox.
  2. Unblocked Spam: if you'd like to help improve the central Razor database, you can! Just move spams that razor misses in this folder, and an automated DreamHost robot will submit them to Razor periodically, and then delete them from the folder.
  3. Blocked Non-Spam: although this should basically never happen, if you do find a non-spam accidentally filtered into your spam folder, you can put a copy of it in here (as well as moving it into your Inbox) and our robot will tell Razor that it made a boo-boo (and again, delete the messages from the folder)! That will hopefully cut down on mistakes in the future..

Last updated: Mar 14, 2005.

User Post (2004-07-10 22:28:27 by btds)
You may also want to take a look at DSPAM: http://www.nuclearelephant.com/projects/dspam/ . It uses various statistical tests to classify spam as spam, instead of SA's rule based filtering. I have written up a quick guide on installing DSPAM on DH: http://www.lalkaka.com/dspam/
User Post (2004-02-08 11:21:29 by xunu)
In reply to dgotilla's post on 12/23/03: NO IT DOES NOT! This is what it means: Copy the non-spam message into BOTH your Inbox AND the "blocked non-spam" folder. The robot will then take the message from the "blocked non-spam" folder (NOT your Inbox!), submit it to Razor, and delete it from the "blocked non-spam" folder. The suggestion of ALSO copying it to your Inbox, or any other folder where you'd like to save the message, is to enable you to keep a copy of it for yourself...
User Post (2003-12-23 05:55:05 by dgotilla)
This page implies that by moving an email message incorrectly labeled as spam from the Spam folder to EITHER the Blocked Non-Spam or to my Inbox I'll be 'teaching' razor not to identify messages like that as spam anymore. Is this correct? Does moving the message to the Inbox have the same effect?

If so, why is there a Blocked Non-Spam folder at all? And why are the messages placed in this folder deleted? This seems very counter-intuitive and not user friendly at all. If I'm going to the trouble of teaching Razor that a piece of mail is not Spam, it follows that I don't want that message (and future messages like that) deleted (or marked as spam).
User Post (2003-11-22 00:41:27 by pav-admin)
I opted to start using razor a couple of months ago. Curiously it seems to have taken some time to start working (a few days, possibly a few weeks; I just now noticed that it has been active). Looking back over the last 2 months I found that a few bulk maiilings from vendors I deal with were filtered as SPAM, but nothing critical. I also see a few things get through the filter each day but the vast bulk of the junk is getting caught.
User Post (2003-09-27 00:27:58 by diva)
I'd second Kerch's comment - Razor works *fairly* well, but it's not 100% accurate. Each day, I'd estimate about a dozen spams or so get past it, and 2 or 3 non-spams get caught by it. And my I add that having it automatically delete the wrongly blocked non-spam is really annoying?! I can only tell it that it guessed wrong if I'm willing to lose that message - i.e. not if it's something genuinely important!
User Post (2003-09-01 16:20:31 by webspiffy)
I revised Richard Donkin's excellent SpamAssassin setup guide: http://webspiffy.com/archives/2003/09/spamassassin/
User Post (2003-08-31 19:16:51 by ozmonkey)
I've had the razor filter turned on for a few months and it hasn't caught a single spam to date. No false positives. No true positives. No nothing. So you say it's working for you? Why isn't it working for me? ....grumble grumble...
User Post (2003-08-30 02:36:04 by rdonkin)
Just use SpamAssassin, it has a great detection rate (99% or so) and low false positives (tunable by the user) - it includes a large number of filtering techniques, including Razor and DCC (similar concept), and also keyword rules, obfuscation rules (spammers try to hide keywords e.g. by breaking them up with bogus HTML) and blacklists. The important point is that no one rule is enough to cause an email to be classified as spam, and SpamAssassin is highly configurable as and when different rules become more or less useful (e.g. Osirusoft recently went under and decided to classify ALL IP addresses as spam relays!) Through tuning of the rules you can reduce the false positive rate and white list key domains or email addreses. Auto whitelisting and Bayesian filtering are also included.

You can find out more at http://spamassassin.org - also there are some hints on installing SpamAssassin on Dreamhost at http://donkin.org/bin/view/Main/SpamAssassin
User Post (2003-08-26 07:04:27 by djlewis)
I did a month-long test of Razor on DreamHost with a particularly spam-ridden account. (Roughtly 3000 pieces of spam in that month.) Razor seems to catch about 50% of the spam (could be 40%, could be 60%, I did not count the unblocked spam in detail) and there were no false positives. There were one or two mass mailings that I might have opened, but no great loss if I miss them. Most importantly, none of the personal e-mail, mailing lists or commercial e-mail that I subscribe to was tagged as spam.

So, that's not bad, but not that great either. Obviously Razor alone is not the solution, but in conjunction with a good whitelist system, might cut things down a lot... with ~zero~ false positives, of course, which is an absolute requirement in my book.
User Post (2003-08-23 03:58:38 by gbdk)
Razor works well --- Just to even out the comments on this page: I'm using this same Razor spam filter with my mailbox here on Dreamhost and it works very well. It doesn't catch everything, but a lot. And so far, it hasn't caught anything that it shouldn't have. I am very happy with this filter. Users who dislike it can switch it off; the default setting for new users is off.
User Post (2003-08-22 07:13:01 by armadaadmin)
This never ever works. I get about 50 emails a day all for viagra, etc. And I follow the instructions to move them, BUT....it does not work....
User Post (2003-08-22 06:40:53 by mimsw)
This is a joke. All of my emails from Dreamhost Support are being sent to DH-Spam. ????? Nuff said.
User Post (2003-08-15 13:32:42 by kerch)
"Blocked Non-Spam: although this should basically never happen, if you do find a non-spam accidentally filtered into your spam folder..."

So they say! I have had reports with too many graphics called spam. I have had pictures from my mother called spam. I have had important time sensative messages called spam. Razor does filter out alot.. but CHECK THE FOLDER REGULARLY or risk loosing important stuff!