You can mark unwanted messages as Junk and add the senders address to the Blocked Sender list, so future messages from that address are moved into the Junk Email folder.
But what if the From address is blank? How can you block an address that doesn't exist?
Easy, create a rule to check the sender address.
This works in both Outlook on the web and Outlook desktop software and you can use one rule with an Exception or two rules.
Use One Rule
Create a rule to delete all mail except if the sender address has an @ sign.
I recommend testing the rule first by moving mail to a new folder then after confirming there are no unintended consequences, edit the rule and change it to delete the messages.
If you are using a Microsoft Exchange Work or School account, add /ou to exceptions. The address for senders on your Microsoft Exchange server will not have an @ (at sign) in the From address.
If you have other rules, this should be the last rule in the list and all of the previous rules should have Stop processing rules, otherwise you'll end up with duplicates.
Use Two Rules
If you prefer to use two rules, the first rule checks to see if the sender address has an @ sign, and moves to Inbox. (Yes, you can do that!) Don't forget to add Stop Processing rules.
The second rule deletes all mail that is not processed by earlier rules.
As with the single rule, if you have other rules the @ sign rule will be next to last and the last rule will delete all mail. The previous rules should have Stop processing rules, otherwise you'll end up with duplicates.
If you are using a Microsoft Exchange Work or School account, add /ou as word in the @ rule. The address for senders on your Microsoft Exchange server will not have an @ (at sign) in the From address.
