Mail app on MacAir with hotmail account, shows ALL messages as unread!

Hello!!!! I just installed OS Capitan on my MacAir. Before i didn`t used to use the mail app on the computer but now i wanted to. I have a hotmail account, so I opened it and right away it started downloading every message since i opened my account and is showing them as unread, so i have more than 2000 unread mails on inbox but this is not true. If i go to my mail through regular internet browser, the mails are read. What should i do??????? ...... Plus i don't want it to be showing messages from 2013 or earlier, so, can it be corrected??????