why do you allow emails with no sender to be sent in your system? I get emails all day where is say "None" in the sender spot.
Why do you allow emails to be sent with no sender. I get emails several times a day with the word "None" for the sender, when i open the details the sender email address space is blank. How can I block this it is always spam I am surprised you allow this.

Regarding your issue, please follow the next steps:
Go to: Mail > Options > Mail Settings > General > Uncheck the box : “Show sender names instead of email addresses in message lists” > click Save settings
Also, In order to block a specific sender, go to Options – Mail Settings – Spam Settings and add the email addresses in the box below “Block Mail from Addresses I Specify”, then click Save Settings at the bottom, and in case you receive unwanted emails in the Inbox, mark them as Spam.