[exim] Is sender verification possible on a server that is u…

I have a dedicated server running exim. It works great, except I
can not get a smarthost setup to work in combination with sender
verification.

On the server, I have sender verification enabled, as a means to
reduce spam. It generally works well. The ACLs are just the ones
from Debian/Ubuntu:

/etc/exim4/conf.d/acl/30_exim4-config_check_rcpt:
   deny
     !acl = acl_local_deny_exceptions
     !verify = sender
     message = Sender verification failed

/etc/exim4/conf.d/acl/40_exim4-config_check_data:
   deny
     !acl = acl_local_deny_exceptions
     !verify = header_sender
     message = No verifiable sender address in message headers

Now I would like to configure this server as a smarthost, so it will
forward emails from my desktop computers (without static IP or DNS).
Also, I'd like to have unique mailnames for each desktop, like
<hostname>.mydomain.org, to better identify where the mail originated
from. But these domains do not really exist, they would be "fake"
mailnames to identify the various desktop computers.

Now, the server rejects all such emails because sender verification
failed. I can see that this is sensible. But it is not what I want.
I wanted sender verification only for non-authenticated users. The
spam protection is (for me) not relevant for authenticated users.
They are assumed to be trustworthy.

I'm not sure if what I'm trying is possible and sensible. Am I
completely on the wrong track here? Are there a better way to
achieve something similar?

All the best,

     Mario Emmenlauer

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