all my servers stopped sending email to hotmail and yahoo, it gives no error in /var/log/exim_mainlog, but the mail never arrives. The interesting thing is that I tried pinging yahoo.com and hotmail.com from the SSH client within my server and it returned me "reply from ..... MY IP! not yahoo's or hotmail's whereas pinging all different kinds of websites gave me the correct IP, (and to them I can also email fine...) so it seems to be a problem on my servers part to correctly identify yahoo or hotmail (and maybe more?).
I added reverse DNS from my IP to the servers hostname but it still gives the same results.