The ongoing recession is having a harmful effect on data security, according to a study of senior IT staff by email security firm Proofpoint.

Half of those surveyed considered that their ability to protect corporate data has been harmed by budget constraints. But budgets alone are not the only problem, since 42 per cent said that increased layoffs were making it more likely that employees will steal information, and 18 per cent had investigated such a case in the last year.

Overall email was still seen as the most risky technology when it came to data leaks, with more than a third of companies suffering a damaging leak via email, up from 23 per cent in 2008. Standard email systems were making IT managers the most nervous, but concerns over mobile email were nearly as prevalent.

To combat the worries over data leaks by email, companies are increasingly scanning email systems, either remotely or using staff. Of the firms polled 38 per cent had staff checking internal emails, up from 29 per cent in 2008.

Overall more than half of the firms questioned have disciplined staff over violation of email policy and 31.6 per cent have fired someone.

Social networking sites were also causing increasing concerns. More than two-thirds of firms have a policy on social networking in the workplace, and this rises to more than four out of five with firms employing more than 20,000 people.

Larger companies were also more likely to fire staff over their use of social networking sites. More than one in five large companies have fired a staff member over social networking use in the last year, compared with three per cent for firms with less than 5,000 employees.