Recommended SPAM Settings in SmarterMail

We recommend the following settings for SmarterMail 4.x and higher.  

1. Login as the System Admin
2. Go to Security
3. Go to Anti-Spam Administration and click the Spam Checks tab 

 We also recommend that when assigning weights to the various SPAM Checks that you use increments of 10.

Declude (Leave unchecked if you not have Declude)
Low Probability of Spam weight = 10
Medium Probability of Spam weight = 20
High Probability of Spam weight = 30

SPAMAssassin
This is a single Thread Windows client that can handle approximately 20,000 emails per day.  If your server processes more than this you may want to use SPAMAssassin in a stand-alone Linux configuration.

Bayesian Filter

Weight = 10 (SPAM weight assigned to an email if it fails Bayesian filter test)
Max. Memory to allocate for filtering = 10MB
Message required for filter update  = 500

SPF       
Pass     weight = 0     Senders IP is valid for senders domain
Fail     weight = 30     Senders IP is not valid for senders domain
Soft Fail     weight = 10     Senders IP is questionable for senders domain
Neutral     weight = 0     No strong statement can be made for or against senders IP
PermError     weight = 0     The SPF record could not be processed.
None     weight = 0     SPF is not commonly adopted therefore, we suggest setting this to 0

Reverse DNS
weight = 10

RBL: SpamCop
weight = 10

RBL: SpamHaus SBL
weight = 10

RBL: SpamHaus XBL
weight = 10

Additional RBL’s can be added and weights applied.

To enable a SPAM Check, click the check box associated with the various SPAM filtering option you want applied to your incoming emails.

You can also enable “Blocking” of emails that fail individual SPAM checks.  As an example, enable Blocking for Reverse DNS, if an incoming email message fails only the Reverse DNS test then, the message is assigned a weight of 10, if the SMTP Blocking Weight Threshold is set to 10 then the message is Blocked.

In order to adjust the weights of the various SPAM checks, click on the Edit link on the right of each SPAM Test item.  You can edit the values and then click Save to implement the changes or clicking Cancel to close the Edit dialog without saving changes.

On the Filtering tab the default settings are shown below:

Low Probability of Spam weight = 10
Default Action:     Prefix subject with text
Text to Add:     SPAM-LOW

Medium Probability of Spam weight = 20
Default Action:     Move to Junk E-Mail folder
Text to Add:     SPAM-Medium

High Probability of Spam weight = 30
Default Action:     Move to Junk E-Mail folder
Text to Add:     SPAM-High

Once, you are comfortable with your SPAM settings you may want to change the default action on the High Probability from “Prefix subject with text” to “Delete the Message”.

Enable Greylisting
This feature bounces unrecognized incoming emails that are not included in either the Trusted Sender list or the White Lists. 

If the incoming message is received by an unknown sender the server will bounced the initial message, when a valid email server retries sending the message after the Block period (default 12 minutes) and within the Pass period (default = 240 minutes) then the email is accepted.  This creates a Record expiration for that email which is by default = 36 days.  If another email is received from this same sender then this resets the Record expiration to 36 days.    

If the messages is received by someone in the Trusted Sender list or the White Lists then the message bypasses Greylisting feature and is then processed by only Anti-Virus Administration settings and then delivered.

Block Incoming and Outgoing SMTP connections 
The idea behind SMTP Blocking of Incoming and Outgoing email is to filter out Spam messages before they are delivered to the Spool.

To enable Incoming and Outgoing SMTP Blocking, log in as the System Administrator, go to Security, Anti-Spam Administration, and Spam Check page.

Enabling Incoming SMTP Blocking can apply Spam filter checks such as SPF, Reverse DNS and RealTime Blacklist.

To configure Blocking of Incoming SMTP connections, select the Spam checks you want applied to Incoming email from the Spam Check page. Once, your selections are made, click the SMTP Blocking tab.  The Spam filtering checks that were selected on the Spam Checks page will be displayed under the Current Incoming Weights.  In order to actually enable the Blocking feature, click the Spam Blocking Enabled Check Box.  Next, you can edit the Weight Threshold under Incoming Options, so that when an email arrives and it exceeds the Weight Threshold value the email is blocked and never delivered to the Spool.

For the SMTP Blocking of Outgoing email, Spam filter checks are applied to outgoing email prior to being put in the Spool.  There are additional Spam checks that can be selected such as: Declude, SpamAssassin, Custom Headers, and the Bayesian Filters in addition to those available for blocking of Incoming SMTP connections.

To configure the blocking of Outgoing SMTP connections, select the Spam checks you want applied to outgoing email from the Spam Checks page. Once, your selections are made, click the SMTP Blocking tab.  The Spam filtering checks that were selected on the Spam Checks page will then be displayed under the Current Outgoing Weights.  In order to actually enable the Blocking feature, click the Spam Blocking Enabled Check Box.  Next, you can edit the Weight Threshold under the Outgoing Options, such that when an outgoing email exceeds the Weight Threshold value the email is blocked and never delivered to the Spool.

Then finally, click the Save.

This article was orginally published at http://tinyurl.com/7j59969