This is just normal untainting, nothing impossible about it.
>From the top of my head, maybe replace the $local_part in the
offending line with
${lookup{${local_part}}dsearch{/var/lib/mailman/lists}}
Not tested, not guaranteed to work, but you get the idea. Check the
exim documentation for more d
Do proper validation of that local_part.
Read the docs; there are indices.
--
Cheers,
Jeremy
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