Milter-greylist

hello,

i just installed milter-greylist 1.5.5 on a linux machine
with sendmail 8.12.11

i have try sending mails from yahoo and hotmail, everything
works fine with yahoo, greylisting and when yahoo retries
the tuples get auto-whitelisted. however, emails from
hotmail just seem to be rejected, sendmail sends the same
message on my maillog file: "[...] reject=451 4.7.1 Greylisting
in action, please come back in 00:10:00"

however, i get a "Delivery to the following recipients failed"
message almost instantly in my hotmail account.

any of you has experienced the same problem? any idea of
how to solve it?

javier