Answering to particular message in mailing list

[Sindhu Hosamane]

This might be a dumb question but I really can't figure out how to reply to ANY 
existing thread or post on the this hadoop mailing list . As far as I've 
understood I can post threads to u...@hadoo.apache.org . but how to reply to 
one particular post? There's no reply button, also reply-to or reply-all from 
my mail produces undeliverable mail message .