Nemx Power Tools for Microsoft Exchange

Review submitted by Patricia Cardoza, Cardoza Solutions

Over the past few years, SPAM and viruses have taken over many corporate email systems. Many companies report that over 50% of their incoming email messages are SPAM. When you add the numerous email viruses that circulate every day, those numbers can swell to 60-70% of incoming email.

There are a wide variety of products system administrators can use to fight SPAM and viruses. One product that integrates both SPAM protection and virus protection is Nemx Power Tools for Microsoft Exchange.

The installation process for Nemx was quite simple. Once Nemx is installed, you can configure its options through the Exchange System Manager. Navigate to the Exchange Server container, right click on Nemx Power Tools for MS Exchange Server, and choose Properties (figure 1). You can then configure all of Nemx’s options.

Figure 1. Use the Properties dialog to configure your preferences.

A few of those options include:

  • SPAM Manager: You can choose four different types of SPAM management. These include: RBL Blocking, Header Blocking, Subject Blocking, and Address Blocking
    • Header Filtering: You can filter for a variety of header situations including:
      • Blank Recipient Fields
      • Blank Originator Fields
      • From Domain is not valid
      • Identical To and From fields
    • RBL Blocking: You can choose from eight different included RBLs or add your own.
    • Subject Blocking: Enter any subjects you want filtered by Nemx.
    • Address Blocking: You can enter a list of addresses to automatically block. If you have lists of existing addresses, you can import them directly into Nemx.
  • Content Filtering: You can block email messages based on phrases within the email body or filter attachments by extension. More than twenty attachment types are blocked by default and the System Administrator can control which attachments are filtered and which are not.
  • Friendly Domains: If you have specific domains you never want Nemx to filter, you can add them to the Friendly Domains tab.

Nemx works quite well. Over seven days the performance of Nemx “out of the box” with no configuration tweaks yielded the following results. 

Total Incoming Messages

Nemx SPAM

Non-Nemx SPAM

Nemx Viruses

Non-Nemx Viruses

Legitimate Email

464

392

29

32

0

11

Nemx uses three different categories of filtering: RBL, message header, and category. The breakdown of the Nemx SPAM messages is as follows:

RBL Violation: 316

Header Violation: 36

Category Violation: 40

Most Exchange Administrators have very strong feelings one way or another on RBL (real-time blackhole lists). While they can be quite helpful and can block the majority of SPAM, they can also block legitimate email. RBLs work by identifying an IP address, address range, or ISP name that’s previously been identified as allowing SPAM to be freely sent through their servers. The advantage of RBL blocking is that it can often stop SPAM from a wide range of IP addresses in one fell swoop. However, the effectiveness of RBLs is quite dependent on the integrity of the RBL administrator. Many RBLs depend on consumers to report IP addresses that are being used to relay SPAM messages. If a consumer reports an address that has recently closed an open relay or reports the wrong address by mistake, an address can often remain on an RBL for some time unnecessarily. For example, an entire IP block owned by a major ISP was once blackholed for quite some time because of inaccurate reporting.

One of Nemx’s options allows System Administrators to send all suspected SPAM to a specific mailbox. The System Administrator can then use the Nemx form to delete or release the SPAM (see figure 2).  After you’ve been using the system for a few weeks, you’ll probably find that Nemx has a very low false positive rate. In fact, over the three weeks I’ve been running the product, it has not caught one false positive. That’s a better percentage than the majority of SPAM filtering products on the market.

Figure 2. Release or Delete the message from the quarantine notification message form.

If you don’t want to send suspected SPAM to a mailbox, you can also choose from a variety of other options including sending a response, appending text to the subject or the message body, or simply deleting the message.

When using Nemx for Antivirus protection, you can choose to clean or delete the virus. If you choose to allow Nemx to clean the virus and it fails, Nemx will delete the virus and add a notification to the message letting the recipient know a virus has been removed. Unlike many other antivirus products, Nemx isn’t configured to send a virus notification to the sender and recipient of the virus infected message. These messages aren’t needed in the majority of the cases because rarely does a virus infected email come from the address it purports to be from.

After several weeks of use, I highly recommend Nemx. It’s stable, highly configurable, and very effective. For more information or to obtain Nemx Power Tools for Microsoft Exchange visit Nemx online at www.nemx.com.

Updated May 11 2008
Copyright Slipstick Systems. All rights reserved.
Send comments using our Feedback page

Home | What's New | Exchange Server | Outlook | Utilities | Bookstore
About Slipstick | Feedback | Privacy Policy | Site Map | Archived Pages | Link to Us | Advertise