SPAM Tools

[Matthew]

As hosts, you are probably aware of all the junk/spam email that accounts for a high % of email on your mail servers.

How do you handle this? I have been both sides of the line before. Part of me thinks all email should be unfiltered for clients because when you do filter email, they are happy until 1 legit email gets blocked and then you have to run for your life.

When it's unfiltered they seem to be crying out for emails to be filtered.

If you do filter out their spam, what tools work best for you? Do you just use blacklists to compare with? Which ones? Do you use Spam Assisin? Bayesian filtering?

Let us know the run down of what works well as spam is a real pain.

 

[Will]

Is there any spam solution that can prepend the subject line of an email? Something like [BULK] so the user can set up rules in their email client to do with it what they wish? Noone can complain about deletion of emails then because they could use a "quarantine" folder to check their spam before zapping it.

 

[Matthew]

This is a common feature on spam filtering. When you filter spam there are many options on what to do.

One example like above is to mark the subject with something. I have used ***SPAM*** in the past.

Also you can add something in to the email header which sends it to the junk mail folder in Outlook.

Other methods are to tag email that is 75% probably to be spam and delete/quarantine emails that are 99% to be spam.

The main problem is finding the spam as RBL's and Bayesian filters only catch a few % of SPAM emails and the rest get through.

From my study of dealing with spam I found that a setup of 2 mail servers would be needed. The first mail server would use RBL's to filter email and also trained Bayesian filters. These are the least processor intensive. Once these have been filtered off then it passes on to Spam Assisin which takes a good chunk off and then on to the receiving mail server.

It's tempting to use a service like spamstopshere.com where they activley update a database every 10 minutes. This database has URL's, phone numbers of any mail that has been manually checked and is considered spam.

For example you have an email that sells Viagra. It says call this number 180012345678. Any email with that matching number is removed. The same for an email with a URL in that says your going to paypal but actually sends you to an IP address which fools some users. They just filter out that IP address and with in 10 minutes of that spam starting to be sent, the URL is blocked and no more emails pass through the system.

Apparantly this blocks a very high % of spam.

Spamstopshere says that 1 in 100000 good emails are blocked but also argue the point that if you have 1000 spam messages in your in box then there is a good chance you might delete a few good emails by accident with being frustrated each day and hitting the delete key so much. I happen to agree with that comment and have my self deleted a few emails by accident and had to ask people to resend a message.

They recommend compleatly deleting those emails in that list and then for the last few % caught by RBL lists and phrase filters you can tag them and check them accordingly to manually review them.

Heck... spam is quite a big task to sort!

 

[Will]

I'd delete the 2% and add the headers / subject pre-pend to let the user choose what to do. Makes most sense to me.

 

[Matthew]

I found a great anti SPAM service which uses the MailFoundary server. Basically you route all email through the spam filter server and it forwards on the cleaned email to the mail server. It's great because the server is on a live update with a team behind it who constantly monitor spam and block bad URL's they find from emails etc... Also saves on processing power needed because of the huge drop of the amount of email hitting the actual mail server. Also it virus scans the email too.

Just to give you an idea... I had an old mail box that I stopped using 2 years ago which was bombarded with spam and about 1 good email a month. Since moving on to the anti spam setup not 1 single spam message has come through. It's amazing!!!

 

[wsac]

Matthew what service is that?

 

[Matthew]

It was from easy@... easyat.com. Unfortunatly there are no reports or control panel, although the price is very good at $19.95 and I believe that allows 500000 emails per month to be scanned.