Postfix force sender ("From:" field)

Hello,
We have Linux post server with Postfix running on it and 5 domains.
Everything is working fine, except one thing. I was wondering how can I force user X to be able to send email ONLY as X@domain1.com, but NOT as X@domain2.com for example. I.e. how can I create map user --> email , and force every user to be verified against this table.

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Thank you in advance