Several third-party software developers have created products for handling large attachments across low-bandwidth connections. All the products perform some type of compression to offset the effect of sending or downloading large attachments from a server.

C2C System's MaX Compression installs as an add-on to Outlook, so you can easily remove and reinstall it as required. (You can obtain the product for a 30-day free trial from http://www.c2c.co.uk.) I checked MaX Compression's effectiveness by verifying documents' file size before I attached them to messages against the size of the messages (content and attachments) after I sent them. I found, for example, that MaX Compression reduced a 1040KB PowerPoint presentation to 806KB and a 929KB Word document to 584KB. The degree of compression achieved seems to depend on the type of documents that are attached and the amount of graphics they contain, but these results show that you can reduce large attachments by almost 40 percent.

You can configure MaX Compression separately on each PC, or you can create and store a common configuration file on an Exchange server. You configure the utility on a PC through a property page that the program adds to Outlook's Tools, Options menu, as Screen A shows. You can set up client systems with a wide array of options. For example, I chose to compress only files larger than 100KB and told MaX Compression to ignore anything that had a .zip or .exe extension, because these files might already be compressed. With MaX Compression, you can compress attachments into a standard Zip file or into a self-extracting executable, as Screen A shows. The software includes the code you need to extract files from an executable, but the extraction code adds about 60KB to the message, so I chose the standard Zip format.

On a server, MaX Compression stores the configuration file, compdb.c2c, in the \MailCompression directory under the \Add-Ins network share. You manipulate the configuration file with a MaX Compression utility, which you see in Screen B. You can use the file to send default options to individual PCs. My server runs on a Microsoft Cluster Server (MSCS) cluster, and I had trouble convincing MaX Compression that Exchange was active on the cluster. Apart from this hiccup, the installation was simple, and configuration took only a couple of minutes.

Another compression product is Dynamic Technologies' CompressMail for Microsoft Exchange (http://www.compressmail.com), which is available as a client-only (Standard Edition—SE) and a client/server (Enterprise Edition—EE) solution. Unlike MaX Compression, CompressMail is available for both 32-bit and 16-bit MAPI clients. The software performs compression on client systems or on the server. CompressMail EE runs as a Windows NT service that monitors a selected set of mailboxes. CompressMail EE compresses attachments on outgoing messages without user intervention and compresses incoming messages that contain attachments to reduce download times across low-capacity links.

Traveling Software takes a different approach with LapLink Enterprise Exchange Accelerator (http://www.laplink.com/ products/ea/ea.asp). This product speeds up message downloads by directing them through a separate proxylike server. The server provides information to users, such as the names of waiting messages and the size of attachments, and lets the user selectively download messages. Exchange Accelerator compresses attachments during download to reduce network usage. Exchange Accelerator is best suited for environments in which many clients use dial-in connections to reach their mailbox. It can be dreadfully frustrating to double-click an attachment only to realize that it's a megabyte or more in size and will take several minutes to download. Outlook doesn't provide a standard way to cancel a download, so the only option is to terminate the call and reconnect.

None of these technologies is likely to be a perfect match for any organization, but they all provide some help for low-bandwidth environments. When you're evaluating these products, consider license fees and additional support costs and thoroughly test any solution before deployment. Also, be aware that server-side processing for compressing and decompressing messages can affect message delivery times unless you install additional hardware.