Article 15 of the GDPR, gives data subjects the right to access personal data held about them by a data controller, usually via a subject access request (“SAR”).

Messages sent via a workplace messenger which involve the data subject would likely have to be disclosed as part of a subject access request if they do more than simply identify the requestor.

ICO guidance provides that for information about an individual to constitute personal data, it must go beyond simply identifying the individual and actually “concern the individual in some way”.  For example, messages sent by or to the data subject simply asking what time a seminar/meeting is at would arguably not ‘concern’ the data subject.

The employer (as data controller) could consider asking the data subject to narrow their request if there are a significant number of messages involving the data subject. This is in accordance with Recital 63 which provides:

“where the controller processes a large quantity of information concerning the data subject, the controller should be able to request that, before the information is delivered, the data subject specify the information or processing activities to which the request relates".

Data protection can be a difficult area and you should either contact the ICO or obtain specific legal advice if you receive a SAR and you are unsure what data needs to be disclosed.