SmarterMail comes with several industry-standard anti-spam options that can help keep mail systems running smoothly. However, while SmarterMail's anti-spam can help block up to 95% of all spam from entering or leaving a mail server, spam administration is not a "fire and forget" task. Mail administrators will need to keep an eye on incoming and outgoing spam and there may need to be additional configuration and management to adjust settings to keep mail flowing freely as spammers frequently change tactics. In addition, other services such as the Cyren Anti-spam add-on may be worthwhile investments as a multi-tiered solution is the best course of action when it comes to dealing with spam. The more checks an administrator has in place, the better equipped a mail server is when it comes to dealing with spam.
In addition, below you will find some recommendations for the various spam settings SmarterMail has to offer. Please keep in mind that these are only suggestions. Administrators can, and should, keep an eye on these settings and adjust them, as necessary, to concoct a viable anti-spam solution for their end users. Other options, such as the Cyren option discussed above, may be necessary to help keep a mail server free from spam.
Applies to SmarterMail 8.x - 14.x
Follow these steps to review your spam settings:
- Log in to SmarterMail as the system administrator.
- Click the Security icon.
- Click Antispam Administration in the navigation pane.
- Click Spam Checks tab.
We recommend using increments of 10 when assigning weights to the various spam checks. To enable a spam check, click the check box associated with the various filtering option you want applied to your incoming emails. 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.
Low Probability of Spam weight = 10
Medium Probability of Spam weight = 20
High Probability of Spam weight = 30
SpamAssassin based Pattern Matching
This is a multi-threaded, proprietary client based on SpamAssassin technology. If your server processes a great deal of messages, then you may want to consider using SpamAssassin in a stand-alone Linux configuration.
Bayesian Filter
Weight = 10 (spam weight assigned to a message if it fails Bayesian filter test)
Max. Memory to allocate for filtering = 10MB
Message required for filter update = 500
SPF
Pass weight = 0Senders IP is valid for senders domain
Fail weight = 30Senders IP is not valid for senders domain
Soft Fail weight = 10Senders IP is questionable for senders domain
Neutral weight = 0No strong statement can be made for or against senders IP
PermError weight = 0The SPF record could not be processed.
None weight = 0SPF 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 RBLs can be added and weights applied.
You can also enable “blocking” of emails that fail individual spam checks. For 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 addition, the defaults for the Filtering tab are as follows:
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 delays unrecognized incoming emails that are not included in either the Trusted Sender list or the Whitelists.
If the incoming message is received by an unknown sender, the server will reject the initial message and ask the sending server to retry at a later time. When a valid email server retries sending the message after the block period (default 12 minutes) and within the pass period (default = 240 minutes), 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 message is received by someone in the Trusted Sender list or the Whitelists, then the message bypasses greylisting and is only processed by only antivirus settings before delivery.
SMTP Blocking
The idea behind SMTP blocking of incoming and outgoing email is to filter out spam messages before they are delivered to the spool. 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 Checks tab. Once your selections are made, click the SMTP Blocking tab. The spam filtering checks that were selected on the Spam Checks tab 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.
Once completed, click Save.
