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Yet another field, reply_mail_last_time, showed a similar disparity. This field contained the time when a member had last replied to a message from another person on Ashley Madison. 5.9 million men had done it, and only 9700 women had.
This implies an upper bound on the number of affairs between men and women facilitated on AshleyMadison.com is 9700. Even by the standards of dating sites, this seems impossibly low, a "success" rate of 1 in 500 just for a reply.