Are Sticky Posts Good UX?

We've all seen sticky topics in online forums - a post which is forcibly stuck to the top of the list by the author(or moderators) of said post. Example:

I have a case now whereby we have an application where one person sends notes to another, the author can choose if this note will be sticky or not, based on the importance of the content, however the viewers don't have the freedom to 'unsticky' any note.

This means that if a sticky note is no longer relevant for one particular viewer, they are not able to 'unstick' the note themselves. I see this as a UX problem of usability freedom.

How could this be dealt with? Could attaching ('nonsticky') red flags to important notes and then filtering the list by that be a solution?