Block Unwanted Email in Outlook

For a single nuisance sender, Outlook’s blocked-sender list is appropriate. For phishing, malware or organisation-wide unwanted mail, report the message and use Microsoft 365 security controls instead of relying on each user’s local list.

In Outlook

1. Select the unwanted message.
2. Use the Junk or Block sender action available in your Outlook version.
3. Confirm future messages from the exact sender are routed to Junk.

When blocking is the wrong tool

• If the sender address is spoofed, blocking that displayed address may not stop the campaign.
• If many users are affected, administrators should investigate message headers and use tenant-level anti-spam/anti-phishing controls.
• Do not block an entire legitimate domain because one account was compromised unless the business impact has been assessed.

For suspicious mail, use the organisation’s Report phishing workflow so the security team receives the evidence needed to investigate.