Hello. i have a big problem with activation lock?

Hello. Please what can i do to get ride of this activation lock. I have an iphone 8 plus ... we have used an apple id before that my not be supported now or email may not be supported any longer. The apple id was. (****@mailna.co) and i know the password but it says this apple id is locked due to security reasons. guides me to unlock it on iforget website but it says its not valid or not supported. .. iam %100 sure of my id and pass but i think apple may not support this kind of emails for example @mailna.co anymore!

Please how can i unlock my device thanks. .. regards.

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