Outlook - prevent sending of emails without a subject matter

Greetings Outlook gurus. I currently run MS Office 2007. Is there an option in Outlook or a macro I may utilize, to either stop or warn me, of sending an email without a subject matter present? I sometimes have done that by accident and I think it is much more professional to always have a subject matter description of the email present. Thank you in advance and Happy New Year to all.