Instructions on how to redact HRC emails include the following tidbit: "The rules below apply not only to private individuals sending emails to HRC, bur also to government officials using private email accounts…"

Sounds like private email accounts were all the rage.

https://foia.state.gov/Search/results.aspx?searchText=redaction&beginDate=&endDate=&publishedBeginDate=&publishedEndDate=&caseNumber=