When a user receives an email notification about having a new PM they can click on the PM link in the email to purportedly read the message. This presents a problem when that user's inbox is full as the messages are held until the user frees up some space and then releases the on-hold message(s). This process is not clear in those cases because the user is merely presented with a message that says: You are not authorised to read private messages that are on hold.

This also marks the message as read even though it really hasn't been read.

A way to make it clear on how the user can actually read their message should be provided. Even a link to take the user to the Inbox for further details might be enough.