How does it suits me ?
I do not gain anything having nemapredaje and osman76 warned for secret diplomacy.
It doesn't suit me that no one cares about the email notification, no one cares because it's not what we are talking about.
Following your logic, why would osman even post on nemapredaje wall, if nemapredaje already knew it anyway ?
But speaking about SD, posting on someone wall can be considered SD even if it's about an already known information.
For example, if you agree on the game chat to make a truce, but also talk about the truce on your wall, it's still SD; because any discussion should be made in the game chat, SD rule.
Therefore it doesn't matter if nemapredaje received an email or not to tell him it's his turn. If osman posting is considered SD, then it is SD, we don't care about the CC email.
Question is therefore, only, is it secret diplomacy to tell someone else in a freestyle game that he can play because it suits you ?
Grey area, and as far as I know it hasn't be discussed before.
It's borderline at least.