Men say too many legit emails = spam
From He Spammed, She Spammed:
"Men were more frustrated, offended, by e-mails from companies they may have done business with but haven't given permission" for e-mail, said Scott Knoll, vice president of marketing solutions at New York-based DoubleClick.
"And even if they do give permission, men react strongly to getting too many e- mails from companies.
"Men tended to think being flooded by legitimate companies was more offensive to their sensibilities than receiving pornographic spam. The sheer quantity of legitimate but unwanted e-mail is turning men off to this marketing channel, Knoll said."