Perhaps the overall document was reviewed based on a diff, and so the section regarding email clients wasn't highlighted to reviewers, since it hadn't changed.

Perhaps the overall document was reviewed based on a diff, and so the section regarding email clients wasn't highlighted to reviewers, since it hadn't changed. And/or there wasn't any versioning applied to the email technology section, so subsequent updates to the recommended-email-clients package haven't yet been pulled into the document. (this is somewhat tongue-in-cheek; but conceivably some of the techniques that contract reviewers use are not-too-dissimilar to code review. Perhaps it really all is completely manual based on physical documents, but hopefully not..)