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Setting Safe and Blocked Senders in Office 365

To add email addresses or domains to the Safe Sender or Block Sender list in Office 365, follow the steps below:

  1. Log in to the O365 Portal at Enter your username as "" when logging in.
  2. Access the "Outlook" section of the portal by clicking the "waffle" icon in the upper left corner and clicking the "Outlook" tile.
  3. Click the "Gear" icon in the upper-right and then click the "View all Outlook settings" link (towards the bottom).
  4. On the left, click "Mail" > "Junk email".
  5. Use the resulting form to set Blocked senders and domains or to mark Safe senders and domains.

Note: Safe Sender lists are limited to 1000 entries and must be specified as full e-mail addresses because adding Safe Sending domains is not supported. Blocked Sender lists are limited to 500 entries, which can be full email addresses and/or email domains.