4. All subsequent emails from that sender will arrive without further challenges.

The best use of eTrust is to have it scan your email folders (and outgoing emails) for email addresses of people you know. You can also manually add senders to your list.

Alternately, eTrust can send a challenging message to new senders. When they reply to the challenge eTrust will approve them.

Pros:

• Very, very little spam g

Cloudmark SafetyBar

Uses its user network to identify spam and phishing attempts -- does not rely on Bayesian filters.a Whenever a single user blocks or unblocks a specific message, Cloudmark Desktop stores tht information to help you reduce the spam you receive.

Pros:

• Two heads are better than one.

• Users build a reputation by setting accurate blocks, otherwise their decisions hold less weight.

Cons:

• Users in the Cloudmark network might not agree with your definition of spam -- and vice versa.

Ella for Spam Control

Using associative memory (in which the memory is accessed by its content instead of an explicit address), Ella for Spam Control learns by surprisingly few examples what spam, and what important mail looks like for you.

Pros:

• Can organize all mail into folder you specify.

• Ella's mistakes can be reversed easily -- and Ella keeps learning.

Cons:

• Only works with Outlook and Outlook Express.

• Given the problems of larger associative memories it is not clear how well Ella performs with its memory filled with lots of email.

• Custom categories cannot be defined in Ella.

eTrust Anti-Spam

Unlike much of the other Outlook spam filtering packages on this list, eTrust uses the Challenge/Response protocol to isolate spam.

When a Challenge/Response system sees an email from somebody you've never corresponded with before, the system will follow these steps:

1. Quarantines the email.

2. Send a "challenge" email to the sender to confirm that the sender is a real person (and not a mailing robot or spammer of any kind).

3. Upon receipt of a valid "response," the original email is released from quarantine.

4. All subsequent emails from that sender will arrive without further challenges.

The best use of eTrust is to have it scan your email folders (and outgoing emails) for email addresses of people you know. You can also manually add senders to your list.

Alternately, eTrust can send a challenging message to new senders. When they reply to the challenge eTrust will approve them.

Pros:

• Very, very little spam ge

Cons:

• Users in the Cloudmark network might not agree with your definition of spam -- and vice versa.

Ella for Spam Control

Using associative memory (in which the memory is accessed by its content instead of an explicit address), Ella for Spam Control learns by surprisingly few examples what spam, and what important mail looks like for you.

Pros:

• Can organize all mail into folder you specify.

• Ella's mistakes can be reversed easily -- and Ella keeps learning.

Cons:

• Only works with Outlook and Outlook Express.

• Given the problems of larger associative memories it is not clear how well Ella performs with its memory filled with lots of email.

• Custom categories cannot be defined in Ella.

eTrust Anti-Spam

Unlike much of the other Outlook spam filtering packages on this list, eTrust uses the Challenge/Response protocol to isolate spam.

When a Challenge/Response system sees an email from somebody you've never corresponded with before, the system will follow these steps:

1. Quarantines the email.

2. Send a "challenge" email to the sender to confirm that the sender is a real person (and not a mailing robot or spammer of any kind).

3. Upon receipt of a valid "response," the original email is released from quarantine.

4. All subsequent emails from that sender will arrive without further challenges.

The best use of eTrust is to have it scan your email folders (and outgoing emails) for email addresses of people you know. You can also manually add senders to your list.

Alternately, eTrust can send a challenging message to new senders. When they reply to the challenge eTrust will approve them.

Pros:

• Very, very little spam g

• Ella's mistakes can be reversed easily -- and Ella keeps learning.

Cons:

• Only works with Outlook and Outlook Express.

• Given the problems of larger associative memories it is not clear how well Ella performs with its memory filled with lots of email.

• Custom categories cannot be defined in Ella.

eTrust Anti-Spam

Unlike much of the other Outlook spam filtering packages on this list, eTrust uses the Challenge/Response protocol to isolate spam.

When a Challenge/Response system sees an email from somebody you've never corresponded with before, the system will follow these steps:

1. Quarantines the email.

2. Send a "challenge" email to the sender to confirm that the sender is a real person (and not a mailing robot or spammer of any kind).

3. Upon receipt of a valid "response," the original email is released from quarantine.

4. All subsequent emails from that sender will arrive without further challenges.

The best use of eTrust is to have it scan your email folders (and outgoing emails) for email addresses of people you know. You can also manually add senders to your list.

Alternately, eTrust can send a challenging message to new senders. When they reply to the challenge eTrust will approve them.

Pros:

• Very, very little spam g

When a Challenge/Response system sees an email from somebody you've never corresponded with before, the system will follow these steps:

1. Quarantines the email.

2. Send a "challenge" email to the sender to confirm that the sender is a real person (and not a mailing robot or spammer of any kind).

3. Upon receipt of a valid "response," the original email is released from quarantine.

4. All subsequent emails from that sender will arrive without further challenges.

The best use of eTrust is to have it scan your email folders (and outgoing emails) for email addresses of people you know. You can also manually add senders to your list.

Alternately, eTrust can send a challenging message to new senders. When they reply to the challenge eTrust will approve them.

Pros:

• Very, very little spam g

4. All subsequent emails from that sender will arrive without further challenges.

The best use of eTrust is to have it scan your email folders (and outgoing emails) for email addresses of people you know. You can also manually add senders to your list.

Alternately, eTrust can send a challenging message to new senders. When they reply to the challenge eTrust will approve them.

Pros:

• Very, very little spam gets through

• No good mail is junked.

Cons:

• Takes time

• Increases traffic on the network

• Spammers can still pretend that they belong to a trusted domain -- if they know which ones are on your list.

Junk Out

Junk Out uses Bayesian statistics to determine spam and learns with every message. It also contains additional filters to tighten things up. In addition, it can contain a "whitelist" of friends and acquaintances whose mail is never spam.

Pros

• Has a very high spam detection rate

• Uses advanced Bayesian statistical analysis

• Easy to use yet highly configurable

Cons

• Can be slow and resource hungry

• Doesn't fully recognize international languages

• Not the most advanced Bayesian filter engine

MailFrontier Matador

MailFrontier combines a "content-scoring" filter system, a network of users who indicate which emails are spam, and challenge/response. The different approaches work surprisingly well together although the overall spam detection rate is nothing to write home about.

Pros

• Combines multiple anti-spam tactics

• Includes community filters, sender challenging and adaptive content filtering

Cons

• Filtering not as precise as some other packages

• Doesn't work with all email programs

• Challenges can be a nuisance

(End of Part One of Two)