Hi Stratos,
To find the Internal Blocked Senders list, go to Settings and click on Content Filtering. You'll find a filter titled "Internal Blocked Senders".
In version 16.x, any time you block a sender all subsequent emails should be sent directly to the Junk Email folder. Can you confirm whether the email addresses you've blocked appear in the 'From specific addresses' and 'From address' conditions?
Andrea Free
SmarterTools Inc.
877-357-6278
www.smartertools.com