Access
Copilot summarised emails labelled confidential despite the rules
In early 2026 a bug made Microsoft 365 Copilot Chat process and summarise emails with confidentiality labels, although organisations' data protection policies explicitly excluded them. The bug lasted for weeks.
Microsoft 365 Copilot Chat is the AI assistant built into Microsoft's office services, and it can summarise a user's emails. Organisations can use confidentiality labels and data loss prevention (DLP) policies to keep automated tools away from certain messages. From 21 January 2026, however, a bug made Copilot Chat process and summarise emails with confidentiality labels in users' Sent Items and Drafts folders, even though the policies in place excluded them.
Microsoft acknowledged the problem in a service alert in early February and began rolling out a fix in stages. It became widely known in mid-February, after BleepingComputer reported it. According to the company, a code issue allowed items in the two folders to be picked up by Copilot despite the labels. It did not say how many users or organisations were affected.
On 19 February Microsoft said a configuration update had been deployed worldwide for enterprise customers, and on 20 February that the fix was working in most affected environments. The company stressed that the bug did not give anyone access to information they were not already authorised to see. In Microsoft's account, then, the emails did not reach anyone unauthorised; the problem was that the AI processed content the organisation had explicitly excluded. According to The Stack, Microsoft did not answer whether any data had crossed organisational boundaries.
What can we learn from it?
When an AI assistant has access to our mailbox, part of our protection depends on the provider's code: a label or a blocking rule only protects us as long as the software applies it correctly. Labelling is still useful, but it is better if it is not the only line of defence. In Confiella the model has no access to email, files or the web: it only receives the request the user has reviewed and approved. Keep client correspondence and case documents somewhere the assistant can reach only when the task needs it.
Sources
- BleepingComputer: Microsoft says bug causes Copilot to summarize confidential emails
- The Stack: 28 days later, Copilot is probably not ingesting 'confidential' email anymore
This article is based on the public sources listed. If you find a mistake, write to us: [email protected]