Using New Outlook on Windows for personal email, calendar, and contact management
Hello,
The quickest fix is to add one server-side rule in Outlook on the Web that deletes anything whose message header contains allohopedomain.uk. This works even when the From: line looks empty or keeps changing, and it bypasses the normal Block command that needs a valid sender address.
Sign in at outlook.com in a browser. Select the settings gear at the top right. Open Mail in the left pane. Open Rules. Choose Add new rule. Give it a name. For the condition choose Message headers include, then type allohopedomain.uk. For the action choose Delete. Turn on Stop processing more rules if you see it. Save the rule. New messages from that source will be removed silently instead of piling up in Junk.
About the No sender address part:
Spammers sometimes send with an intentionally blank From line or a forged display name. Email standards still allow delivery in that case, which is why Outlook shows no sender address and why the Block feature can say cannot block. Your new header based rule does not rely on the From field, so it will still catch them.
If you want, reply with the full message header from one of those junk emails and I will confirm the exact text to match so the rule is as precise as possible.