Tempe-based Arizona State University began notifying 4,000 students Aug. 16 that their email addresses "were accidentally" revealed in a data breach, according to CBS affiliate KTVK.
The incident happened in late July when a university official sent bulk emails to students about renewing health insurance coverage. In the emails, the employee did not hide the students' identities.
In a statement, ASU said, "The only items of protected health information released were the students' email addresses. No other PHI was released."
Since the incident, ASU has adopted new procedures to improve data protecting, including establishing more review and approval levels for mass email distribution, KTVK reports.