[exim] Blacklisting users from sending out mails.

Hi,

I wanted to know under which all smtp related acls I can add code to block
outgoing mails from a specific sender? I am planning to add the below given
condition under acl_smtp_mail:

---------------
    deny
        senders = /etc/exim/exim-blacklist-senders
        message = This account is blacklisted from sending out mails
---------------

Is their anyother acl where I can have the above condition added?

Also I am planning to add a spoof prevention condition for outgoing mails
[only allow mails if sender domain part is hosted in the server]. I could
find that we can add it under acl_smtp_mail, is there any other acl under
which I can add the condition?

Regards,
Soumya