Patch your Outlook 2010 Beta

If you are trying out the Office 2010 Beta, there seems to be a bug in Outlook that increases the size of some messages sent through it. More info is available at their blog - Issue with message sizes in Outlook 2010 Beta.

They have also released a patch for the same, you can get it from Fix for issue with message sizes in Outlook 2010 Beta.

I personally like the new Office 2010, also make sure to check out their Outlook Social Connector, its cool. Right now it supports Outlook Social Connector for LinkedIn