You can't meet everybody. But how to tell them?

Is your e-mail full of requests from old colleagues, acquaintances or completely unknown people who would like to invite you for a coffee or schedule a personal phone call to talk with you about your work and your industry or introduce you to their services? If you are just starting your career, you are probably glad and open to meeting with everybody. The flow of similar invitations will, however, grow with the years of your experience and successes and if you should meet everybody, you would do nothing else. So let's look at how to assess whether you should meet someone or not and how to say no appropriately.