Can’t send a message to a blocked friend on Messenger with a contact never blocked

hello

i am getting this "Can't send a message to a blocked friend on Messenger." on "outlook.com" web messenger

i never blocked that contact.

my mail id is finishing by "live.com" & the other contact by "hotmail.com"

i tried with both IE11 & firefox 25, same issue.

i tried with skype with my live id & the other contact with outlook.com web messenger with any of the browser, no issue.

so don't know if the issue related to hotmail id, confused...