I've been an Outlook Express user for years, just switched to Outlook 2003. I really can't figure out what's going on here:
I have several POP email accounts set up on Outlook, including one for my school, which does not allow relaying to outside domains. Generally, I use a VPN to circumvent this problem. In Outlook Express, if I wasn't connected through the VPN, the email would simply come back to me with a denial message from the server. Outlook, however, sends the email--without asking--from another one of my email accounts. I've tinkered around with this, and it only happens when I use that particular email address and try to email outside of my school's domain.
I wish it would just come back as undeliverable... Any thoughts?