When sending email, the CST Accelerator client hooks into the winsock.dll file, much like most anti-virus programs, and compresses emails and compressible attachments there. The compressed email is then redirected to the accelerator where it is decompressed and sent to the email server it was originally intended for. Incoming mail is done much the same way. The command to "check mail" is redirected to the accelerator. The accelerator checks the clients email, compresses it and sends it on to the customer. For this to work, the email client must be turned off when CST is started, and CST must be restarted after enabling the email acceleration. Normally this is not a big deal, since the CST will start before any client would in a normal situation, but it's an easy step to skip when testing.
As an example, here was an email message with 1.4 Megs worth of .html and .txt file attachments, all VERY compressible. The savings on these types of attachments would be the highest. The usage statistics were reset before sending the email, and these are the results. Bear in mind, this is with a network connection, not a modem. Modems already have the ability to compress data built into the hardware, so the savings could be less, depending on what type of connection the user had.
