The compression ratio for a session in which you send a number of messages with Zip file attachments will be much lower 5 percent to 10 percent isn't unusual. The same is true of Microsoft Word 2000, which compresses graphics inside .doc files. However, Outlook doesn't handle graphics in documents and presentations generated by earlier versions of Microsoft Office so elegantly. Therefore, you'll do well to send those files in Zip files. Controlling Flags and Properties Microsoft designed Outlook to be a full-featured client, and enabling features incurs some overhead.
Many features rely on updating flags or properties to reflect a message's current status.
Any overhead becomes more obvious when communication links are slow, but fortunately, you can reduce Outlook's network requirements in this area. Outlook treats every message as an object that has a set of properties, which MAPI defines. Familiar properties include message subject, the recipients, and date sent. Other properties are less obvious, and some aren't essential if you just want to send and receive email. For example, Figure 2 shows some detail from my Inbox.