Exchange Online Delete Blocklist Email before delivery

Question

Hi Everyone,

We are using Exchange Online, we block certain email IDs using Anti-Spam policy. These emails are being marked as spam and following the Spam policy settings.

What is the best way to drop these emails before delivery?

Thanks

Answer 1

If you want to delete only specific messages from specific senders, then I would create a mail flow rule to delete those messages and not block them in the anti-spam policy

https://learn.microsoft.com/en-us/exchange/policy-and-compliance/mail-flow-rules/mail-flow-rule-procedures?view=exchserver-2019

Answer 2

Here is detail information about how EOP works:

If you want to prevent email from delivery to user mailbox, you need to use "Mail flow rules" or "Anti-Spam" to block emails. Both of them could redirect email to quarantine instead of the intended recipients. You can also configure policy to delete them directly.

Here is a screenshot about configuring Anti-Spam policy to delete email before delivering to mailbox:

Answer 3

If the requirement is to "block certain email IDs".
Use a Mail Flow rule to do this
or block by sender in the anti-spam policy
https://learn.microsoft.com/en-us/microsoft-365/security/office-365-security/create-block-sender-lists-in-office-365?view=o365-worldwide

Create blocked sender lists in EOP