Mark message as read

This endpoint allows a user to mark a message as read.

Note that:

<ul class="list-bullet"> <li class="font-xsmall"> Individuals or organisations can only access their own data, and must be enrolled for the <a href="https://www.gov.uk/correct-your-business-rates" target="_blank">Find and check your business rates valuation</a> online service. </li> </ul>