Even with existing impediments, lawmakers still bellyache that the torrent of e-mails they get every day is more than their staffs can handle. So the House's managers are adding what they call a logic puzzle to the hurdles that constituents must already scale before writing e-mails to members. In addition to the Zip code test and others, the system now used by a growing number of lawmakers also asks would-be e-mailers to solve a simple numbers problem.