There is a bug in the Microsoft Office 2010 Beta that increases the message size of some e-mails messages sent from the Microsoft Outlook 2010 Beta. The Office team has been hard at work building a fix for this issue, which is available for download now...

Download Outlook 2010 Beta fix for 32-bit Office 2010

Download Outlook 2010 Beta fix for 64-bit Office 2010

This fix prevents future messages from consuming unnecessary space, but doesn’t resize existing messages. If you reply or forward an existing message that is affected by this bug, it remains enlarged. To help reduce the impact of large messages on your Inbox and mailbox storage quota, you can also run Conversation Cleanup (new feature in Outlook 2010) on large folders. On the Home tab, in the Delete group, click Clean Up. Also, consider starting new message conversations or threads when possible.