Outlook Mail on the web lets you block messages from individual senders, as well as entire domains. Here, we'll show you how to use Outlook.com and Outlook Online to block specific domains, and how to create rules or filters to block other types of messages.

To ensure that Outlook Mail on the web rejects messages from all email addresses in a specific domain:

Select Settings (the gear icon ⚙️).

Select View all Outlook settings.