How many emails do you send a week? How many people do you work with? What do you estimate the total number of emails send out by your company, including auto replies to CV's, out of office responses, etc., to be?

Take the chance to review your signatures and add in messages and links that can add value to the reader. That may be "follow us on Twitter @EmploymentOffice for our latest vacancies" or "join our LinkedIn group" or even an odd testimonial from a client or candidate. It's free marketing and volume marketing at that. Why not have a group discussion at the next team meeting you have and ensure there is a strong consistent message being sent out?