I'm not sure what Microsoft's thinking was in this regard, but the "Block
Sender" option that has long been available in Outlook Express is missing
from the RC2 (and RC1) Mail beta.
That button is essential for anyone who actively participates in USENET
conversations, and doesn't want to have to create a rule to get rid of the
posts of every troll they encounter. And in some groups, like sports
communities during playoff season, the trolls can become a huge problem.
That's a feature that should really be restored. I notice that there's a
junk mail option now in the beta, but this doesn't provide the same
functionality - like the ability to immediately block and remove offending
posts and posters.
Outlook Express was never ideal for binary downloads, but was fine for
participating in USENET conversations. Without the restoration of that
option, it will become largely useless in even the non-binary groups.