U of I Box, Can't receive confirmation email
While Box email is not being blocked by the University email relays, if you are redirecting your email to another address it is likely being blocked by them. The confirmation email is short on content and contains a link, which might appear suspicious to those spam filters.
If it is blocked enough times, Box will add your @illinois.edu account to a suppression list.
Since Spring of 2016 we've seen a majority of the addresses on the suppression list belong to the following:
The Help Desk can contact Box to remove you from the list, but that doesn't guarantee that those services won't continue to block any new confirmations sent. If that is the case, we will ask Box to manually confirm your account.