Junk Filters


Can someone explain to me in more detail how the Junk Filters are implemented?

The reason I ask is that I’m observing some odd behavior which I can’t quite explain, so hopefully someone can explain for me.

Here’s the story:
I have only a few email addresses set up on my account, including one for myself and one for my dad.

I wanted to set up the DreamHost “Junk Filter” for my dad’s account, but not for my account (I’m using another mechanism to sort my spam). However, both our email address were on the same domain.

So, here was my solution:
I created a new subdomain, filtered.origdomain.com (where origdomain.com was my original domain name). I turned on “Junk Filtering” for this subdomain but not the top domain.
I then created a new shell account for my dad, and created a new email address "dad@filtered.origdomain.com", and set up his old address to forward all mail to this new address (as well as store the mail as a backup in his old account). I figured I would test this setup by comparing the old account to the new account to see how the junk filter is working.

Here’s the odd part:
So far nothing has been deposited in the “Junk Mail” folder in Webmail. In addition, things have been disappearing from the old account, not the new account, the one on which I enabled the Junk Filter! I’ve checked the old webmail, and there is no “Junk Mail” folder there, and I know “Junk Filtering” is not enabled for the original domain.

I can’t think of a good reason that mail would arrive on the new, filtered account, but not at the old, unfiltered account. The most commonly blocked messages have been messages that my dad periodically gets from eBay about saved searches, so I know they are being sent to the original address, and they should be arriving at both accounts.

Can anybody explain what is happening and how I can fix it? If I get no replies here, I’ll ask support.


DreamHost’s junk filter doesn’t check mail forwarded from one account to another. For me, I have maillist@mydomain.com that forwards to many people, including me@mydomain.com. me@domain.com has a filter, but because the mail came through maillist@mydomain.com, DH’s JunkFilter doesn’t check it.

A solution for you is to:

  1. Enable Junk Filtering for the domain (don’t bother with your subdomain approach).
  2. Log into your webmail account and set the filter settings so high that everything will get through.
  3. Log into your dad’s webmail account and set the filter settings low enough to catch the spam.




Thanks for your reply. I figured it had to be something funny about the forwarding setup that was causing it to not filter properly on the @filtered.domain.com account. I’m still a little unsure of why it started filtering the @domain.com account though.

I may try your suggestion (which is a pretty good idea) for now and see how it works. However, the filtering that was (showhow) happening on the original account wasn’t very impressive, so if I get the time I think I’ll go with the instructions I found for installing spamassassin in my shell account.

  • Ben


I’m not sure that e-mail that goes to the mXXXXXX accounts even touches your home directory, so I’m not confident that a personal installation of SpamAssassin will work on an e-mail only account.

It looks like you’ve already thought of this, seeing how you’ve posted a query for converting your dad’s account. Why “convert”? What’s wrong with just creating a new shell account and then update your dad’s mail settings and then ditch the mXXXXXX account?



Yes, I do realize that you can’t set up a personal SpamAssassin installation on an e-mail only account. What I’m going to do is delete my dad’s email only account, and just update the old email address to point to the new account. That’s why I created the new account as a shell account in the first place (so I wouldn’t have to create another account if the Junk Filter didn’t work out).

I guess there’s no good reason to “convert” an account… the issue is transfering old mail (stored in IMAP) to the new account, and reassigning the email address to point to the new account. I can transfer the mail via IMAP, but I was hoping to avoid the “download and upload to the same server” (although that’s not a huge issue).

I was also concerned that if I reassigned the email address away from an email only account, it would scrap the account along with my dad’s email, but if I transfer the email before reassigning the email address I think it will work out.