Yeah, we had the same thing at my previous company, except it was sent from external address. However opened it once in the mobile app where it wasn't clearly visible.
Since then I was generally reporting everything that came out of external address and I wasn't expecting (like when I did a flight reservation just before or alike). Funny thing is that the company also used external providers sometimes (for surveys etc.), so I might have flagged some relevant mail as well (and probably didn't attend a few important surveys).
Also reported and blocked mail about the progress of the company founder candidating for the US president (which was true at the time, but the mails looked a bit fishy, were from an external address and where unsolicited and spammy anyway ... but later learned from the others they were legit).