With Outlook 2003, since I have been working with two accounts, I sometimes observed that the default account is not used and this causes the email not to be sent, from my default location. So, as soon as I change that Outbox email to use the default account, from the drop down on the top of each email, it works.
This is a bug. Has someone experienced that before. If yes, do you know if this has been fixed in 2005?