gh-100991: fix email header `References` and `In-Reply-To` being treated as unstructured #137564

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pkgconf 2.3.0_1 is already installed and up-to-date. To reinstall 2.3.0_1, run: brew reinstall pkgconf

xz 5.6.3 is already installed and up-to-date. To reinstall 5.6.3, run: brew reinstall xz

gdbm 1.24 is already installed and up-to-date. To reinstall 1.24, run: brew reinstall gdbm

tcl-tk@8 8.6.16 is already installed and up-to-date. To reinstall 8.6.16, run: brew reinstall tcl-tk@8

HOMEBREW_NO_INSTALLED_DEPENDENTS_CHECK is set: not checking for outdated dependents or dependents with broken linkage!