@Danthar Thanks for your input. Yes, I am a bit worried about implementing such a stuff on mailbox level and I guess there are many things which will can be done wrong. But also I could not come up with a proper flow how to handle it by the actor itself.
Now that you point again in that direction I think maybe I could have two stages of messages. The first one, plan-a-refresh, will set a flag on the actor. If another plan-a-refresh message occurs while that flag is true, it will be ignored. The first message but will not also set the flag but self-tell a do-a-refresh message. That one will be at the end of the actor mailbox queue and all already queued plan-a-refresh messages will be ignored due to that flag. The do-a-refresh message will when do it and reset the flag.
I am doing this because there are external events which will cause like 50 to 100 actors to notify this one actor to do a refresh and it would be nice to do the refresh after the last message or at least not as often as that number.