Technology

Using the Block Sender Function in Microsoft 365

Last modified 12/4/2024

User’s can block people or domains so messages from those people or domains no longer show up in the users Inbox.

When a user or domain is listed as a blocked sender, any messages sent to the user from the blocked sender will be routed directly to the user’s Junk Email folder.

How to Add a Blocked Sender 

  1. Open an internet browser and navigate to office365.illinoisstate.edu.
  2. Log in to Office 365 via Central Login.
    1. For more information about Central Login at ISU, please refer to: Central Login
  3. Once you are at the home page, click Outlook on the left. The application icon looks like a blue envelope outlook icon.
  4. Once Outlook is opened and you are at your inbox, click the gear icon at the top-right corner gear symbol, which is your settings.
  5. Upon clicking the gear button you will see a new pane emerge on the right side. At the bottom of that new pane, click the View All Outlook Settings button.
  6. In the settings window, click on Mail and then click Junk Email.
  7. On the right, you will see Blocked senders and domains. To add someone to the blocked senders list, click the + Add button. Simply type in the email address in the field and press Enter on your keyboard.

You have now added a user to your blocked senders list.

How to Remove a Blocked Sender or Domain 

  1. Open an internet browser and navigate to office365.illinoisstate.edu.
  2. Log in to Office 365 via Central Login.
    1. For more information about Central Login at ISU, please refer to: Central Login
  3. Once you are at the home page, click Outlook on the left. The application icon looks like a blue envelope outlook icon.
  4. Once Outlook is opened and you are in your inbox, click the gear icon on the top-right corner gear symbol, which is your settings.
  5. Upon clicking the gear button you will see a new pane emerge on the right side. At the bottom of that new pane, click the View All Outlook Settings button.
  6. In the settings window, click Mail and then click Junk Email.
  7. On the right, you will see Blocked senders and domains. To remove someone, click the Trash can icon to the right of the contact’s email address.

You have now removed a user from your blocked senders list.

How to Edit a Blocked Sender or Domain (New Outlook)

  1. Open an internet browser and navigate to office365.illinoisstate.edu.
  2. Log in to Office 365 via Central Login.
    1. For more information about Central Login at ISU, please refer to: Central Login
  3. Once you are at the home page, click Outlook on the left. The application icon looks like a blue envelope outlook icon.
  4. Once Outlook is opened and you are in your inbox, click the gear icon on the top-right corner gear symbol, which is your settings.
  5. Upon clicking the gear button you will see a new pane emerge on the right side. At the bottom of that new pane, click the View All Outlook Settings button.
  6. In the settings window, click Mail and then click Junk Email.
  7. On the right, you will see Blocked senders and domains. To edit one of your entries, click the Pencil icon to the right of the contact’s email address. Edit the appropriate information and press Enter on your keyboard when you are done.

You have now edited a user’s information in your blocked senders list.

How to Get Help

Technical assistance is available through the Illinois State University Technology Support Center at:



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