Party requires different emails for different skins?

[Freudian]

I have used the same email (gmail) for all my four Party skins and it's been working fine. But a few days ago tournament summaries stopped arriving from Multipoker.

So I decided to change the email on Multipoker and everything is working fine. And since I thought my gmail account wasnt working properly I decided to change my Empire and Party ones to the working Multipoker email. When I tried it a box that has the following message pops up.

"The mail-id you want to use is already used by another account. Our Cardroom does not allow same mail-id used by multiple accounts.".

Is this a new thing? Everything has been working fine up until now.