I am using the MessengerManager to send a mail to the customer. However, Users created by this customer that have Admin Rights assigned are receiving the mail also.
Is it possible to send my mail only to the customer?
This is designed behavior, according to the MessengerManager documentation:
"Account ID is alternative to userId and used to specify the APS ID of the account whose staff members must receive the notification."
"AccountID" is used, the message will be sent to all admin staff members of this account. If you want to send email only to one person, you should use
userId - User ID is alernative to accountID and used to specify the APS ID of the user whom the notification is addressed.