It's not the spam folder - it's that there is no rDNS entry for the mail server, so most receiving mail servers will bounce the activation message.
I own the mail server I used to register just now, so I saw this and made a workaround, but most people will no longer be able to register until the host corrects the DNS entries for this server. Here's a sample from the mail log:
sendmail[8902]: sBLEIU0J008902: ruleset=check_mail, arg1=<nobody@8827.vz015.ubiquityservers.com>, relay=70.32.40.136.rdns.ubiquityservers.com [70.32.40.136] (may be forged), reject=553 5.1.8 <nobody@8827.vz015.ubiquityservers.com>... Domain of sender address nobody@8827.vz015.ubiquityservers.com does not exist