require 'net/pop'

mail_server = Net::POP3.new('mail.mailservernamehere.com')

begin
  mail_server.start('username','password')
  if mail_server.mails.empty?
    puts "No mails"
  else
    puts "#{mail_server.mails.length} mails waiting"
  end
rescue
  puts "Mail error"
end