Flag owls - like Outlook mail

Hello, any chance we can have a flag button in owls? 

Essentially like Flag in Outlook mail. 

Or make it a star or tick box, whatever works so that you could mark the owl for yourself? 

Cause sometimes you read an owl, and you want to respond after checking something, or asking someone first etc, but the second owl is unread you cannot reverse it and you cannot mark it and it can get lost in your other owls, especially if you have a site job and get a lot of them a day. 

So IRL in Outlook I would flag the message, it leaves it yellow and gives the wee flag (I am sure you know what I am talking about), that way I know to get back to it later and can go on and read the other messages that are easier/quicker to respond without fearing I will forget about the first one.... so can you do something similar? A flag or star that would mark the owl so you know to get back to it? 

Thank you