I am guilty of this, but it should not be tolerated. What is it? It is not responding to correspondence. If someone sends you an e-mail, leaves you a voicemail, or even sends you a letter, please respond. Even if you cannot do what the correspondence is asking or cannot assist someone in their endeavors, let them know. When you ignore correspondence or do not return a telephone call, it is a sign of rudeness and unprofessionalism. Even if you respond that you will respond later, do it. If you are too big of an organization not to return correspondence personally, hire someone to do it. Someone once told me that success is measured in the follow-up! Remember that there is never an excuse to be rude.