According to a study, about a third of big companies in the United States and Britain hire employees to read and analyse outbound email as they try to guard against legal, financial or regulatory risk.
More than a third of US companies surveyed also said their business was hurt by the exposure of sensitive or embarrassing information in the past 12 months, according to the annual study from a California company specialising in protecting corporate email at large businesses.
"What folks are concerned about is confidential or sensitive information that is going out," said Gary Steele, chief executive of Proofpoint Inc., which conducted the study along with Forrester Research.
The top concern was protecting the financial privacy and identity of customers, followed by compliance issues and an effort to prevent confidential leaks. Businesses ranked monitoring for inappropriate content and attachments as less important.
Steele said on Friday that more companies are employing staff to read outgoing emails of workers who typically have no idea their correspondence is being monitored.
"There are organizations where employees think they can say whatever they want to say and nobody is going to read it"
"It is not something that is broadcast," Steele said. "There are organizations where employees think they can say whatever they want to say and nobody is going to read it."
The survey gathered responses concerning email security from 406 companies in the United States and the United Kingdom with more than 1,000 employees.
In both regions, 38% of respondents said they employed staff to read or otherwise analyse outbound email. In the United States, 44% of companies with more than 20,000 employees said they hire workers to snoop on workers' email.
Nearly one in three US companies also said they had fired an employee for violating email policies in the past 12 months and estimated that about 20% of outgoing emails contain content that poses a legal, financial or regulatory risk.