Do you have to dig through the headers to find that, or is the sender literally email@example.com?
If the former that's pretty standard, it's not a red team, and it's not designed to fly under the radar, just literally a quick stat gathering on how many perform whatever action (as you said, checking hygiene), usually whitelisted by the incoming mail gateways too.
Oftentimes how many+who, but can be just how many to see if training is sticking. Anyone digging through headers is already suspicious.
Apologies if this comes across condescending and I misunderstood, but it seemed like you were saying that's a rubbish practice or something
If it's the latter then.. Wow. Someone is just looking to get good stats to show how great the training was, lol.