For notifications like a mailbox, what design pattern, how do I model my schema objects

In a webapp (ASP MVC), I have a view/page that lists new notifications/incoming messages similar to a list box (picture a mail box, but much simpler) across sessions for users. I understand INotifyPropertyChange and Observables

My scenario: I have a simple Transactions table with a TransactionType, only some transactions with Transaction.Transactype == Approve/Reject need notifications.

How do I model this in the database and the object so that I can pick up these changes, everytime the user logs back in, across session?

Here is what I did,

1. I created a separate Transaction.ApproveTable and I attached a trigger on insert, but I am looking them across the sessions
2. I created an MSMQ journal, but its blocking since its serial from notifying other users. I also have a role notification scenario, where I notify all member of the role.