Sounds like something very simple. Create a job to monitor the table via a TSQL query, and send the mail if conditions are (or aren't) met. What I would do if tasked, however, is probably create a web service to handle the business logic...there are probably other types of sendmail type objects deployed in your company's BLL, so no reason to reinvent the wheel by recreating the mail logic again.
Did I just type this? I can't believe that all of the coders on these dev teams that I work with have me now convinced to leave business logic out of the database! On second thought, use option one. 😀