Psychologists are concerned about the pressure that workers bring on themselves. Dr. Richard MacKinnon spoke with VOA News on Skype. He says that email can be a valuable, time-saving communication tool. But it can also be a source of stress and even anger for many of us. He adds that the stress does not come from the number of emails you get. The problems result from when and how you deal with them. According to the study, there are two very stressful email behaviors. One is leaving email on all day and never signing off. The other is reading and answering emails early in the day and late at night. Checking your email very early in the morning, or checking it late at night, or leaving your email on all day, that has a much stronger relationship with email pressure. So it's not necessarily about how many emails we receive... But not all jobs are equally stressed by email. The jobs most affected by email stress are: marketing, public relations, media and information technology.