Just upgraded from Office 2007 to 2010. We use numerous email addresses in the office. We use a SBS 2008 server, but just have Exchange set as a .local. Default address is set to use company external address. We just use Exchange for storage and calendaring mainly. Quickbooks would use in Outlook 2007 whatever we had set as our default address to email. Now with the 2010 upgrade it always defaults to trying to use the .local address of the Exchange user. We manually change it no big deal, but I'm going to encounter this issue with some of my accountant clients when they upgrade MS Offfice, so looking for answers now.