Content Filtering

This service allows you to control mail flowing in and out of your mail server. By setting up one or more condition-action style rules, you can choose to block or re-route your mail, adjust mail content, execute applications, send new mails and more.

Content Filtering

  • Enable Content Filtering - This controls whether the content filtering is enabled.
  • Content Filter Rules - This is a list of content filter rules that will be used to control mail passing through your mail server. Rules are performed sequentially and some rules may affect subsequent rules. Therefore, you can change the order of the rules to achieve the desired effect.
  • Add Preset - This allows you to add preset content filter rules to help save time and give an indication of the kind of rules that can be created.

Add / Edit Rule

  • Enable Rule - This controls whether the content filter rule is enabled.
  • Name - This is used to uniquely identify a rule in the settings and also as an indication of the nature of the rule. The name is only used in the settings and logs and does not have any effect during the rule being performed on any mails.
  • Conditions - This is a list of content filter conditions for the rule. Conditions are triggers which evaluate to either true or false for a particular mail being filtered. Conditions are performed sequentially and use logical and/or/not operators together with brackets to achieve a logical equation which overall will evaluate true or false. You can change the order of the conditions and the logical and bracket operators to achieve the desired effect. All conditions will not change the mail being filtered.
  • Actions - This is a list of content filter actions for the rule. If the conditions for the rule evaluate true for a given mail, the list of actions are performed. Actions are performed sequentially and some actions may affect subsequent actions. Therefore, you can change the order of the actions to achieve the desired effect.

Add / Edit Condition

All conditions are shown in the table below followed by details of each condition type.

Type Condition Description
No Settings All Emails This condition will always evaluate true. This should be used when you want actions to be performed on all emails.
SPAM Flag Set SPAM flag must be set.
Contains Attachments Must contain one or more attachments.
Substring Match SMTP Sender Matches SMTP Sender must match the substring search.
Any SMTP Recipient Matches Any SMTP Recipient must match the substring search.
SMTP Host Name Matches Remote mail server host name must match the substring search.
Remote IP Address Matches Remote mail server IP address must match the substring search.
Reverse DNS Lookup Matches Reverse DNS lookup of remote mail server host name must match the substring search.
Any Custom Event Matches Any custom event must match the substring search. This option can be used to detect the origin of a mail. The pre-inserted custom events to indicate origin are: ORIGIN-SMTP, ORIGIN-WEBMAIL and ORIGIN-POP3RETR.
Any Attachment Name Matches Any attachment name must match the substring search.
Any Charset Matches One of the character sets used must match the substring search.
Any Header Line Matches Any header line must match the substring search.
Any X-Header Line Matches Any x-header line must match the substring search.
Any Body Text Line Matches Any body text line must match the substring search.
Any Message Text Line Matches Any message text line must match the substring search.
Header Line Match Header Line Matches The specified header line must match the substring search.
Sender / Recipients Exist Sender / Recipients Exist Evaluated based on SMTP sender / recipients existing locally on the mail server.
Value Email Size Must be larger / smaller than the size specified.
Bayesian Score Must be higher / lower than the score specified.
Application Result Application Result Evaluated based on the return value for an application execution.

Condition Type - No Settings

This is the simplest type of condition. Each condition with this type requires no additional settings to be evaluated.

Condition Type - Substring Matches

'Substring Match' conditions evaluate based on a particular attribute value matching the substring search criteria provided.

  • Match Type - This controls what kind of substring search will be performed against the values supplied. This can be one of the following:
    • String Matches - The value must match the substring provided.
    • String Contains - The value must contain the substring provided.
    • String Starts With - The value must start with the substring provided.
    • String Ends With - The value must end with the substring provided.
    • String Does Not Contain - The value must not contain the substring provided.
  • Substring - This is the substring to be used with the given 'Match Condition' during the string search.
  • Case Sensitive - If enabled, the string search will be case sensitive. Otherwise, a case in-sensitive search will be performed.
  • Substring List - This allows a list of substrings to be used in the search instead of just one. The substrings are separated by semicolons (';'). If any one of the substrings matches the search criteria the condition will evaluate true.

Condition Type - Header Line Matches

'Substring Match' conditions evaluate based on a particular attribute value matching the substring search criteria provided.

  • Standard Header Field - If set, the substring search will be performed on the header field selected from the combo box.
  • Custom Header Field - If set, the substring search will be performed on the header field specified in the available text box.
  • Match Type - This controls what kind of substring search will be performed against the values supplied. This can be one of the following:
    • String Matches - The value must match the substring provided.
    • String Contains - The value must contain the substring provided.
    • String Starts With - The value must start with the substring provided.
    • String Ends With - The value must end with the substring provided.
    • String Does Not Contain - The value must not contain the substring provided.
  • Substring - This is the substring to be used with the given 'Match Condition' during the string search.
  • Case Sensitive - If enabled, the string search will be case sensitive. Otherwise, a case in-sensitive search will be performed.
  • Substring List - This allows a list of substrings to be used in the search instead of just one. The substrings are separated by semicolons (';'). If any one of the substrings matches the search criteria the condition will evaluate true.

Add / Edit Condition Type - Sender / Recipients Exist

The 'Sender / Recipients Exist' condition will evaluate based on whether one or more addresses exist locally on the mail server.

  • Who - This controls which addresses we are checking for existing locally on the mail server. This can be one of the following:
    • Sender - The Sender from the SMTP envelope must match the existence criteria.
    • Any Recipients - At least one Recipient from the SMTP envelope must match the existence criteria.
    • Any Recipients - All Recipients from the SMTP envelope must match the existence criteria.
  • Exists - This controls whether we are checking for the given addresses existing. This can be one of the following:
    • Exists Locally - The given address must exist locally.
    • Does Not Exist Locally - The given address must not exist locally.

Condition Type - Value

The 'Value' condition evaluates based on a particular attribute value being larger or smaller than the value provided.

  • Match Type - This controls the kind of size comparison to be performed. This can be one of the following:
    • Larger/Higher Than - The value must be larger than the size provided.
    • Smaller/Lower Than - The value must be smaller than the size provided.
  • Size/Score - This is the value that will be used with the given 'Comparison Type' during the comparison.

Condition Type - Application Result

The 'Application Execution Result' condition will evaluate based on the return value of an application being executed. The application should perform some kind of processing and then exit returning an appropriate value showing the result of the processing done. If the application does not return it will be terminated after a time-out value and the condition will evaluate false.

  • Application Path - This is the file path of the application to be executed. It is perfectly legal to have this path set to a network location. For more information on using network drives, please view the Frequently Asked Questions page.
  • Parameters - This is an optional set of parameters which will be passed to the application to aid in its processing. You can also pass the mail file path as a parameter using the special tag of "%s", allowing relevant processing to be performed on the mail being filtered.
  • Return Value - This is the value range to be compared against the return value given by the application. If the return value is in this range the condition will evaluate true.
  • Hide Application Window - If enabled, the application window will be hidden when executed.

Add / Edit Action

All actions are shown in the table below followed by details of each action type.

Type Action Description
No Settings Remove All Recipients Removes all SMTP recipients.
Set SPAM Flag Sets the SPAM flag in the mail.
Remove SPAM Flag Removes the SPAM flag in the mail.
Stop Content Filtering Stops content filtering. Subsequent actions and further rules are not performed.
Delete Email Deletes the mail from the system. Subsequent actions for the current rule that do not affect the mail directly will still be performed. Further rules will not be performed.
Recipients Redirect To Removes all SMTP recipients and adds the recipients provided.
Add Recipients Adds the SMTP recipients provided.
Send Copy To Sends a copy of the mail to the recipients provided.
Rename Rename Recipients Renames any SMTP recipients that match the substring search.
Rename Attachments Renames any attachments that match the substring search.
Remove Remove Recipients Removes any SMTP recipients that match the substring search.
Remove Custom Event Removes any custom events that match the substring search.
String Add Custom Event Adds the specified custom event to the mail.
Place in Account Directory Tries to deliver the mail to the specified account directory instead of the default 'Inbox' directory.
Rename Sender Renames the SMTP sender to the provided address.
Edit Header Field Edit Header Field Replaces the field text of the specified header field. Adds the field if it does not exist.
Add Signature Add Signature Appends text or HTML code to the base of a mail body.
Strip Attachments Strip Attachments Strips any attachments that match the substring search. Optionally inserts 'removed attachments' message.
Strip All Strip All Attachments Strips all attachments. Optionally inserts 'removed attachments' message.
New Mail Send Email Sends a new mail.
Reply to Email Sends a reply mail back to the SMTP sender.
Send Email to Recipients Sends a new mail to all SMTP recipients.
Add Text to File Add Text to File Appends text to the specified file. Creates the file if it does not exist.
Copy All to Directory Copy All Attachments to Directory Copies all attachments to a specified directory. Does not alter the attachments within the mail.
Execute Application Execute Application Executes an application with the parameters provided.

Action Type - No Settings

This is the simplest type of action. Each action with this type requires no additional settings to be performed.

Action Type - Recipients

'Recipients' actions control the recipients in the SMTP envelope which governs which email addresses the mail is delivered to.

  • Recipients - This is a list of recipients which are to be affected by the appropriate action.

Action Type - Rename

'Rename' actions are performed on a particular attribute based on its value matching the substring search criteria provided.

  • Match Type - This controls what kind of substring search will be performed against the values supplied. This can be one of the following:
    • String Matches - The value must match the substring provided.
    • String Contains - The value must contain the substring provided.
    • String Starts With - The value must start with the substring provided.
    • String Ends With - The value must end with the substring provided.
    • String Does Not Contain - The value must not contain the substring provided.
  • Substring - This is the substring to be used with the given 'Match Condition' during the string search.
  • Case Sensitive - If enabled, the string search will be case sensitive. Otherwise, a case in-sensitive search will be performed.
  • Substring List - This allows a list of substrings to be used in the search instead of just one. The substrings are separated by semicolons (';'). If any one of the substrings matches the search criteria the condition will evaluate true.
  • Rename To - This is what values matching the substring search will be renamed to.

Action Type - Remove

The 'Remove' actions are performed on a particular attribute based on its value matching the substring search criteria provided.

  • Match Type - This controls what kind of substring search will be performed against the values supplied. This can be one of the following:
    • String Matches - The value must match the substring provided.
    • String Contains - The value must contain the substring provided.
    • String Starts With - The value must start with the substring provided.
    • String Ends With - The value must end with the substring provided.
    • String Does Not Contain - The value must not contain the substring provided.
  • Substring - This is the substring to be used with the given 'Match Condition' during the string search.
  • Case Sensitive - If enabled, the string search will be case sensitive. Otherwise, a case in-sensitive search will be performed.
  • Substring List - This allows a list of substrings to be used in the search instead of just one. The substrings are separated by semicolons (';'). If any one of the substrings matches the search criteria the condition will evaluate true.

Action Type - String

The 'String' actions are performed based on the string provided.

  • Account Directory - This is the directory that mail will try to be delivered in instead of the default 'Inbox' directory. If the directory doesn't exist for a particular account, the mail will be placed in the 'Inbox' as normal.
  • Custom Event - This is the custom event that will be added to the mail.

Action Type - Edit Header Field

The 'Edit Header Field' action replaces the text of a particular header field. If the header field is not present it will be created.

  • Standard Header Field - If set, the substring search will be performed on the header field selected from the combo box.
  • Custom Header Field - If set, the substring search will be performed on the header field specified in the available text box.
  • Text - This is the text that will replace the current header field text specified. This option allows the use of field tags, for more information please view the Using Field Tags page.

Action Type - Add Signature

The 'Add Signature' action inserts a signature in the text and HTML body parts of a mail.

  • Text Body Signature - This is the text which will be appended to the base of the text body part of the mail. This option allows the use of field tags, for more information please view the Using Field Tags page.
  • HTML Body Signature - This is the HTML code which will be appended to the base of the HTML body part of the mail. This option allows the use of field tags, for more information please view the Using Field Tags page.

Action Type - Strip Attachments

The 'Strip Attachment' action removes attachments that match the substring search criteria provided.

  • Match Type - This controls what kind of substring search will be performed against the values supplied. This can be one of the following:
    • String Matches - The value must match the substring provided.
    • String Contains - The value must contain the substring provided.
    • String Starts With - The value must start with the substring provided.
    • String Ends With - The value must end with the substring provided.
    • String Does Not Contain - The value must not contain the substring provided.
  • Substring - This is the substring to be used with the given 'Match Condition' during the string search.
  • Case Sensitive - If enabled, the string search will be case sensitive. Otherwise, a case in-sensitive search will be performed.
  • Substring List - This allows a list of substrings to be used in the search instead of just one. The substrings are separated by semicolons (';'). If any one of the substrings matches the search criteria the condition will evaluate true.
  • Insert Removed Attachment Message - This will cause an extra attachment listing all removed attachments to be added to the mail.

Action Type - Strip All

The 'Strip All' actions remove all appropriate parts from the mail.

  • Insert Removed Attachment Message - This will cause an extra attachment listing all removed attachments to be added to the mail.

Action Type - New Mail

'New Mail' actions create new mail to be inserted into the mail server.

  • From - This is the email address that will be used as the 'From' address of the mail.
  • To - This is a list of recipients that will receive the mail. You can add more than one email address separated by semi-colons (';').
  • Subject - This is the subject of the new mail. This option allows the use of field tags, for more information please view the Using Field Tags page.
  • Message Text - If set, this will be the message body of the new mail. This option allows the use of field tags, for more information please view the Using Field Tags page.
  • Message File - If set, the message body of the new mail will be the contents of this file.

Action Type - Add Text to File

The 'Add Text to File' action appends the provided text to a given file. If the file does not already exist it will be created.

  • File Path - This is the path of the file to be appended to. It is perfectly legal to have this path set to a network location. For more information on using network drives, please view the Frequently Asked Questions page.
  • Text - This is the text that will be appended to the file. This option allows the use of field tags, for more information please view the Using Field Tags page.

Action Type - Copy All to Directory

The 'Copy All to Directory' actions copy all appropriate parts of the mail to a specified directory. The parts remain in the mail.

  • Directory Path - This is the directory that all parts will be copied to. It is perfectly legal to have this path set to a network location. For more information on using network drives, please view the Frequently Asked Questions page.

Action Type - Execute Application

The 'Execute Application' action executes a specified application.

  • Application Path - This is the file path of the application to be executed. It is perfectly legal to have this path set to a network location. For more information on using network drives, please view the Frequently Asked Questions page.
  • Parameters - This is an optional set of parameters which will be passed to the application. This option allows the use of field tags, for more information please view the Using Field Tags page.
  • Hide Application Window - If enabled, the application window will be hidden when executed.