If you want to find messages from a specific coworker, click on the filter "Someone's messages":

Then a box with all of your employees will appear. If you have many employees, you can also search for the name of the employee you wish to find. Choose the one, you want to search for. In my example, I choose Vibeke:

Now I will see all the messages I have, that Vibeke is also a part of.

OBS: It is only when the person has started the thread or added a comment to it, that the conversation will appear in the list. Otherwise, the conversation will not show when you search for the employee. This means, that even if the employee you search for is included in the conversation, the conversation will not show, if the employee has not added a comment to it.

As you can see, I have only two conversations with Vibeke. One of them is a day-message, which means it is a message sent on a day in a rota. The other one is a private correspondence between her and I:

You will also have the option to find all messages from a specific coworker in the app. Click on the three dots in the left corner, and click on the filter "Someone's messages":

Again choose the coworker you like. Then you will see all the messages you have, that also include this person. In my example, I choose Vibeke. Now I will see all the correspondences I have had with Vibeke: