When i create a new domain via the Plesk control Panel, then receive the following error.

Failed domain creation: Unable to update domain data: Failed mail post-configuration: Can't create mail domain servie: mailManager->addDomain() failed: mailmng failed: MEAOPO.
PostOffice ---------------------- Debug Info ------------------------------- 0: c:\Program Files\SWsoft\Plesk\admin\htdocs\domains\create_domain.php:146

how can i resolve it, any idea ?

Hello,

If you have the administrator access of the server , login to the server with RDP , type mailenable.msc , from the postoffices , select the domain which you are trying to add and delete it .
Now try creating the domain .

Yes deleting the domain from mail enable post office section will take away your porblem

You will not be able o fix this issue if you are a shared hosting user or a reseller. It seems the domain that will be created already exists in the mailenable records. You need to login to Remote desktop, delete the domain maually from mailenable and try again.

you need to delete domain entry manually for that you need admin access of the server.