Package: exim4-daemon-heavy Version: 4.94.2-6 Followup-For: Bug #528344 Perhaps important to note is that both DMARC and (currently still experimental, but...) ARC both depend on the builtin SPF support. While the SPF "support" by calling an external binary may work for SPF checks at a cost of a fork per ACL test (i.e., some performance penalty), this is not the case for the extra functionality that depends on the builtin SPF support, such as sending out DMARC validation reports, and adding ARC headers (to mitigate the issues with forwarding emails).
Please seriously consider this wishlist item for bookworm already...