[tatersolid]

Outlook also recently changed the default “report message” action in the UI to be “report phishing/malware” instead of “report spam”. This was a terrible design choice; phishing reports from my org’s own user base has increased 4x since the change which is a lot of false positives.

So maybe folks mean to “report spam” on your emails but “report phishing” instead…

[joaopbnogueira]

Could be the reason, but even so, we have really low volume campaigns and mostly to people we actually interact / have a history with. I would assume it would take more than a few accidental hits to trigger this issue.