Every time you email that 8MB attachment to 90 members of staff, the Exchange gods kill a kitten.
Why? Because by dumping an 8MB message in 90 mailboxes, you ate up 720MB of storage on the Exchange server, and I know full well that half those people will never delete it from their inbox. You only have to do this a few times before this gets expensive.
In short, stop it. The shared drive is there for a reason, and I’m running out of disk space to allocate to the mail server.
I’m also running out of kittens.