Because the Attachment Service is so resource intensive, it's a good idea to run it on dedicated hardware.
The BlackBerry Attachment Service runs on each BlackBerry Enterprise Server you install. Most of the time it does a nice job of converting a variety of attachments into a format that is readable on your device. However, every so often you'll find a certain type of strange attachment sends the service to its knees. When this happens, it can impact the entire BlackBerry server, tying up resources and preventing other services from running optimally. In fact, there are instances when the Attachment Service has prevented any communications to or from handhelds while it chugs along consuming all the server's CPU time.
The BlackBerry Enterprise Server provides a way to point a BlackBerry Enterprise Server to another machine for attachment services. By moving the Attachment Service to another machine with either a smaller number of users or none at all, you isolate it from the rest of your BlackBerry platform. When a strangely formatted attachment is read that causes the resources to spike in the arrangement, your BlackBerry users won't even notice (unless, of course, they try to read an attachment while the remote Attachment Service is already pegged!).
The nice thing about moving the Attachment Service is that although a full BlackBerry Enterprise Server installation is required on the remote machine, the actual BlackBerry Service doesn't need ...