Hi @Regina Floyd ,
Did those senders get Email non-delivery reports back after sending email messages out?
As I know, when blocked from Outlook client, it doesn’t stop delivery of junk email messages, but spam to the Junk Email folder, just as this article Overview of the Junk Email Filter said.
If the senders indeed get NDRs, it is more likely that they are blocked from the server side. If you are using Office 365 email account, you might need to remove blocked users from the Restricted Users portal in Office 365. For more information about how to unblock Restricted Users and NDRs, please check:
Email non-delivery reports in Exchange Online
Remove blocked users from the Restricted Users portal in Office 365
Hope these can be helpful.
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