Historical clue formulations

• Keeping in the loop, in a way — 2024-01-31
• Including on an email thread — 2023-06-18
• Sharing mail with, in a way — 2016-02-18
• Keeping in the loop, in a way — 2015-02-26
• Sharing a memo with — 2009-07-05
• Sending a duplicate, for short — 2005-02-06