Letters from the Union of Concerned Scientists, the SPLC, Greenpeace, EDF, etc etc appearing in my mailbox and asking for money, suspiciously about 1-2 weeks af

Letters from the Union of Concerned Scientists, the SPLC, Greenpeace, EDF, etc etc appearing in my mailbox and asking for money, suspiciously about 1-2 weeks after I signed up for an event. That's how.