The University of Hertfordshire has reviewed its procedures after around 2,000 names and email addresses of students were leaked in an email inviting them to a guest lecture.
After realising the error, in November, it referred itself to the Information Commissioner's Office and conducted an internal investigation - which has now concluded with no further action being taken by the ICO.
A spokeswoman for the Hatfield-based university said: 'We immediately reported the breach to the ICO, who decided that it was not necessary to investigate further as the university had in place appropriate processes for dealing with these circumstances.
'The university has reviewed its processes and provided additional appropriate guidance to staff. We take data protection extremely seriously and provide mandatory training on data protection issues which all staff complete as part of their induction to the university, and then refresh periodically.'
An ICO spokeswoman said: 'People have the right to expect that organisations will handle their personal information securely and responsibly.
'Where that doesn't happen, people can come to the ICO and we will look into the details.'
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