Allegedly, on or about 30 December 2013, Mihamina Rakotomandimby sent:
SPAM is very subjective. I saw users subscribing to several newsletters for an event (say XMas) and then in February they're too lazy to cleanly unsubscribe: they just tag the message as SPAM, and they argue it's SPAM because they dont want to receive the messages anymore. Dumb, but true.
I've seen that often enough. When the "this is spam" button simply configures their own software, it's merely a dumb thing to do. But when their mail client's "spam button" *reports* the message as spam, it causes problems for the senders, who did nothing wrong.