Knowledge Essentials - 3Essentials Hosting

Spam Protection: Content Filtering

Article ID: 258

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If you haven't read it yet, we recommend you review the following KB article which provides an overview of 3Essentials spam protection mechanisms, and explains how training the spam filtering fits into the overall 3Essentials spam protection strategy: Spam Protection: Overview of 3Essentials Spam Protection

This article describes how to enable Content Filters,  available to customers who have our most recent plan versions which are hosted on servers.  Once you've completed reading this article, it's recommended your review the following articles which discuss two other weapons available to you to customize your spam fighting arsenal:

If you are attempting to set content filters and you are already using 3Essentials Spam Free Trusted Mail  (details here), see applicable notes at the bottom of this article.

Proceeding with the discussion of content filtering:

To set spamfiltering options for ALL users on the domain, set the domain-wide spam filtering options by:

  • log into the control panel with their control panel user/pw.
  • click on the domain
  • click on the MAIL icon
  • you will be prompted to log into the mail management interface, login in with your Control Panel user/pw again. 
  • once in the SmarterMail interface, click on DOMAIN SETTINGS, and in the pulldown, you'll have these options:
    • DOMAIN CONTENT FILTERING: here you can set up specific words that will cause a mail to be blocked (i.e., "viagra", etc..).  These filters can be set for subject or content, etc.  See the help icon in this interface if you need details on the configuration options. 
    • DOMAIN SPAM FILTERING: here you can adjust the options for how spam filtering will be handled for all users (i.e., if spam, should the subject line be tagged, or should the mail be deleted) and you can add to a list of "trusted senders". 
    • Settings made here will apply to all email users on that domain. 
  • Utilize the ? HELP icon in the SmarterMail Mail Management interface to get more detailed information on configuring content filters.
  • Note, individual users can log directly into their webmail interface (http://webmail.yourdomain.com), and can access the same "content filtering" settings, but these will be applied to JUST that user... these are "user-specific" content filters.  Note, user's DO NOT have to continue to use the webmail interface, this is just where they access the settings... these filters will continue to work, even if the customer uses a standard mail client (like Outlook). 
  • Please note, functions like "moving to folders" are applicable only to the WEBMAIL interface... this means if you set a rule like "if subject contains the word INQUIRY, move to folder called NEW SALES CALLS", this will move the mail to a folder called NEW SALES CALLS that exists ONLY IN YOUR MAILBOX ON THE SERVER, not in your mail client (like Outlook or Outlook Express)... and that folder would only be accessible via the WEBMAIL interface.  If you want rules like this to put mails into folders in your MAIL CLIENT (like Outlook or Outlook Express), you can do this with a slight variation:
    • setting the content filter's action to ADD A HEADER that includes the folder name, then setting a rule in your mail client to check headers and take certain actions, i.e., a rule that says "if header includes X-folder-newsalescall, then move to folder NewSalesCalls".   This way, the content filter tags the header with something the mail client will look for, and it can then take the appropriate action within your mail client, once it's been downloaded to your mail client.  Please check your mail client software's documentation for information on whether it supports creating rules based on header content, and how to implement. 
    • one exception to this is setting a filter to "move to inbox".  You'll find further description of why  you'd set a "move to inbox" filter below.
  • Note - domain-wide content filters supercede (override) user-specific content filters.
Understanding TRUSTED SENDERS and CONTENT FILTERS:
By design, the "trusted senders" list only excludes an email sender from "spam filtering" on the postoffice server. It does not exclude it from content filters... but this can be easily addressed. Content filters are processed in order, and are only processed until a rule is met... for example if I had:

contentFilter1: mails from mike - mark important
contentFilter2: mails with "chocolate" in body - delete

And you (let's say you are Mike) sent a mail to me with the word "chocolate" in it, it would not be deleted... because you, mike, sent me the mail, and it matched contentFilter1 first, and took that action... the mail will not be compared to any other contentFilter.

So, in order to have Trusted Senders ALSO excluded from any custom content filters you create (for example, to search for porn terms), we need to do is add a content filter ABOVE the porn filter, to apply to Trusted Senders... i.e.:

contentFilter1: mails from Trusted Sender list - move to inbox
contentFilter2: mails with porn terms - delete

With this simple addition, the Trusted Senders are now excluded from spam filtering AND are excluded from any content filtering. The "move to inbox" feature is the only "move to folder" configuration that works with your mail client without the need to set up header changes... this is because when your mail client checks your mail, it checks the inbox... so "move to inbox" puts it where it would have gone anyway, and where your mail client would have checked anyway.   Remember, we're only put this filter there to make a mail from Trusted Senders match some a filter, and ensure mail from Trusted Senders is indeed delivered to your inbox, and not be compared to subsequent filters. 

Spam Free Trusted Mail notes

If you are attempting to set content filters and you are already using 3Essentials Spam Free Trusted Mail (details here), understanding the way content filtering works and examining the impact of the order of the filters is critical to avoid any unexpected results.  Content filtering works by comparing each email to the list of criteria in the content filters in order... it starts with the first content filter, and moves downward until it either finds the mail has matched a content filter's criteria, or there are no more content filters.  If a mail matches a content filters criteria, that action is taken, and the mail is not compared to any other content filters.  In other words, the mail is not compared to any other content filters once it is determined it matches a given content filter's criteria.  As such, the ORDER of your content filters is paramount.  If you're using the Spam Free Trusted Mail configuration, and wish to add other content filters, insert them in middle of the two rules implemented with Spam Free Trusted Mail:

  • Allow Trusted Senders (must be first)
  • my additional content filters
  • Not Trusted Senders (must be last, as it is a global type rule, "from address is *.*")
 
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