A program is attempting to send the following email message on your behalf:

Should you receive the following window

 

There is an option set in Outlook (Express) that asks you to verify sending an email any time some program other then Outlook (Express) tries to send an email. Go to Outlook (Express) Tools> Options > Security.

 

You can change this to send without warning, or you can simply select "send" or "don't send".