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Have You Considered?

The amount of customization available in Denes is where much of its power and flexibility truly shows. Consider some of these uses for Denes that may not be directly obvious:

Black Lists and White Lists

Denes not only can act on DNSBLs (DNS Black Lists, e.g. SpamCop), but can also act on DNSWLs (DNS White Lists, e.g. bondedsender.org). Separate actions based on DNS lookups to either deny or accept email are available in the Denes filter. This allows you to take advantage of all DNSBLs and DNSWLs you desire for your situation in a single EIMS filter.

Local DNS Based Lists

Each rule in Denes can have a different domain to lookup. This means it is a very simple matter to create your own custom DNS based lists to handle the special needs of your company, network, customers, and users. For instance, if you want to maintain your own list of remote IPs that you always accept email from, maintain this list in DNS records on your local DNS server (using standard reverse dotted format) and create a Denes rule act on these entries to accept email. Your customization of black lists and white lists just became immeasurably simpler with Denes.

Domain Specific Lists

Using some of the substitution values for DNS lookups available within Denes, it is a simple matter to make custom black and white lists based on different domains you may host. For instance, using the recipient domain substitution, it would be a trivial matter to allow all email into a particular hosted domain. Or, with the MAIL FROM domain substitution, you could create entries in your local DNS to deny all email from particular domains you receive UCE (spam) from. You can even combine multiple substitutions in a single lookup to provide unique options for each domain you host. Denes gives you more flexibility in EIMS than you ever had before.

Web Management of Rules by End Users

The rules document for Denes will dynamically and intelligently detect when changes have been made. This occurs at any time during the operation of EIMS. And, when a change has been detected, Denes will reload the rules document. So, editting your rules for Denes does not require you to quit and launch EIMS after each change; rather, changes can be made directly in place without any interuption to your production email services.

Consider, though, just how simple the rules document format is: it is merely a tab delimited text document. It is a small matter to create a web based interface to manage this document, adding and deleting entries as needed. With the options to create local cusotmizations for each domain you host, you could even create a web interface that your end users manage to manipulate directly the settings that affect their email. Denes makes this all possible.

Test DNS Lists without Affecting Email

Actions to refuse and accept email can sometimes have harsh affects for users and customers. Everyone has experienced the DNSBL that blocks legitimate email. And, there has never been a way to really test this without just blocking email and waiting for users and customers to complain.

With Denes, though, the actions to refuse or accept email are discrete from the actions to make entries in the logs. For instance, to setup a DNSBL that will be blocking email and making a log entry of the blocked email, you actuallly create two separate rules. The first rule will have an action to create the log entry and the second rule will have an action to refuse the email. Don't worry, Denes is intelligent enough to know now to do the lookup twice, either, once for each rule; Denes remembers that a previous rule already performed a particular lookup and will use its internally cached lookup result for subsequent rules on the same complete lookup domain.

With these discrete actions, you can see that it is a minor matter to make rules that do nothing but make log entries without actually refusing or accepting explicitly the email. So, if you have a new DNSBL or DNSWL that you are considering using, you can test it by making a rule to make log entries only. Then, merely perusing the log entries will let you know what email would have been affected by the lookup if you enabled a refuse or accept action based on the lookup. Denes let's you test in your production system without interrupting production operations.

Responses that Include Lookups URLs

Often, when email is refused, the bounce message generated by the remote host contains the refusal response EIMS sends. Each rule within Denes allows you to customize the response sent from EIMs to the remote host. With full support for substitution values, it is a trvial matter for you to include custom URLs and notices based on the email being refused. This aids immeasurably when your users, your customers, or even you need to diagnose why particular emails are being refused based on DNS lookups.

Check the Speed of Your Lookups

One of the substitution values available for use in responses and log entries is the amount of time it took to perform the lookup (in milliseconds). Including the lookup time in log entries is invaluable to deciding which DNSBLs and DNSWLs are performing better and which are responding too slowly. Denes makes it possible for you to decide what DNS lookups work quickly enough for your needs and which do not.

Users Wanting All of Their Email without Filtering

It is inevitable, some users will just not understand that spam filtering is required. Or, they may have client side spam filtering tools that they prefer to use. Consider, it is not a bad idea to accept all email on your postmaster accounts, either. With Denes, you can use recipient domains and recipient usernames to create custom DNS lists to act against. A single DNS entry could allow for all email to a single recipient, a single domain, or a single account name across many domains to be effectively white listed. Denes makes it possible for you to customize your systems to the needs and demands of your services and customers.

We Want Your Suggestions

Please let us know what features and functionality you would like to see included in Denes. The functionality available serves its purpose very well. Though we do have quite a few ideas for additional functionality to add, it is always helpful and much appreciated to have feedback from customers about what can be added to fulfill your needs.

Like all products from Deep Sky Tech., functionality is available in a format that allows the maximum amount of customizability for use in your situations. Every email administrator has different needs and requirements; every mail server requires different and unique requirements to make a server and network as optimal as you require. You can see from the following features, Denes allows you to customize as much as possible in the filter to fulfill your needs for your unique situation. Control of your products and services is the goal of all products you use from Deep Sky Tech.

Features and options in Denes

  • Full, user definable management of all SMTP connections;
  • Custom path to rules document;
  • Intelligent, dynamic reloading of changed rules document;
  • Limitless number of DNS lookups within rules document;
  • Settable rules names;
  • Lookup domains fully customizable in rules document;
  • Support for substitions in lookup domains, including:
    • Remote IP;
    • HELO/EHLO identifier;
    • MAIL FROM username;
    • MAIL FROM domain;
    • RCPT TO username;
    • RCPT TO domain;
    • TLD+1 calculations;
  • Match operators for comparisons in rule determinations, including:
    • IP match with significant bits;
    • Equals;
    • Begins with;
    • Ends with;
    • Contains;
    • MX and IP existence (for SMTP delivery);
    • TLD+1 calculations;
    • Negations on all operators;
    • Existence checking;
  • Per rule setting for only checking non-authenticated and/or authenticated SMTP connections;
  • Per rule setting for using native or more powerful custom Domain Name Resolver (DNR);
  • Support for NS records of type A, MX, PTR, and TXT;
  • Discrete actions to take as result of DNS lookup matches include:
    • Deny email;
    • Allow email;
    • Make error log entry;
  • Custom response codes for SMTP transaction actions;
  • Per rule setting for error log entries;
  • Settings per rule for error log entries support substitution values for:
    • Rule name;
    • Remote IP;
    • Full lookup domain;
    • HELO/EHLO identifier;
    • MAIL FROM username;
    • MAIL FROM domain;
    • RCPT TO username;
    • RCPT TO domain;
    • Lookup result;
    • Lookup time, in milliseconds;
    • TLD+1 calculations;
  • Settings per rule for responses to SMTP transactions support substitution values for:
    • Rule name;
    • Remote IP;
    • Full lookup domain;
    • HELO/EHLO identifier;
    • MAIL FROM username;
    • MAIL FROM domain;
    • RCPT TO username;
    • RCPT TO domain;
    • Lookup result;
    • Lookup time, in milliseconds;
    • TLD+1 calculations;
  • Host name following for MX and PTR lookups and subsequent comparisons;
  • Dynamically and automatically reload any DNS settings changes without need to relaunch;
  • Support for standard and custom DNS Exclusions document;
  • Definable match results for each rule;
  • Lookup redundancies intelligently elimitated directly in filter for maximum efficiency;
  • Definable default responses to SMTP transactions;
  • Settable default error log entry;
  • Choice to deny after MAIL FROM or DATA sections of SMTP transactions;
  • Operation of multiple rules on single email;
  • Does not interrupt operation of EIMS;
  • No quitting of EIMS application required for rule changes;
  • Compatibility with Mac OS 9 and Mac OS X;
  • Compatibility with EIMS and EIMS X;
  • Email notification of error conditions.

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