To add someone to your "Blocked Senders" list in Office 365, please follow the procedure below:

  1. Login to Office 365 at
  2. Click the gear icon in the upper right corner and then click "Mail". This will open the "Options" pane to the left side.

  3. In the left "Options" pane, under "Accounts" click "Block or allow". This will open the "Block or allow" pane.

  4. Ensure the "Automatically filter junk email" radio button is selected. In the "Enter a sender or domain here" field, enter an email address or domain. After you have entered an email address or domain, click the "+" icon to add it to the appropriate list. Finally, when you are finished, click "Save" on the left top.