Client access tables based on SASL-authenticated username

[Nikolaos Milas]

Hi,

Quick question:
Is there a way to create some client restrictions based on the SASL-auth 
username of the client? Or this is only achievable via a policy server, 
like postfwd?

For example, I would like to have restrictions of the form: "Only 
clients authenticated with the SASL-auth username 'secretary' or 'chief' 
will be allowed to submit mail to the recipient address 
allst...@example.com."

I know we can set restrictions based on the IP address of the client, 
but what about the SASL-auth username?

Thanks in advance,
Nick