## script

class User
  MAIL_SERVERS = 3

  def initialize(username)
    @username = username
  end

  def mail_bucket
    1 + (@username.split(//).inject(0) {|sum, x| sum = ((sum << 3) ^ (sum >> 5)) ^ x[0] } % MAIL_SERVERS)
  end
end

while username = gets
  username.chomp!
  user = User.new(username)
  puts user.mail_bucket
end

## results

$ cat usernames.txt | ruby hash_test.rb  | sort | uniq -c
1121 1
1146 2
1084 3