Exchange Admin Center Blocked List is not working
User in tenant still getting spam email that has been blocked from the Exchange Admin Center
Office 365 spam filters marked this message as spam, and then the message was marked as good mail (non-spam) after we processed it. This usually happens when Outlook is set to deliver all messages to the inbox instead of using the Junk Email folder.
Fix the issue
To make sure that Office 365 will filter messages like this, the recipient needs to change the Block or allow setting in Outlook on the web.
- In Outlook on the web, go to Options - Mail - Accounts - Block or allow.
- Choose Automatically filter junk email, and save the setting.