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Blacklisted Relay - Which Setting Takes Precedence?

Anonymous
2017-05-12T14:31:25+00:00

All:

  There is a relay server for another organization that has been blacklisted, however, what I need to know is if creating a whitelist for the IP of the relay takes precedence over adding the sender's email address to a whitelist? Or would the email message still get blocked if we just add the email address to a whitelist? Any help would be appreciated. Thank you.

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  1. Anonymous
    2017-05-12T21:48:10+00:00

    Hi Exchange_Engineer_4L,

    IP reputation filter in Office 365 will check the tenant allow list, tenant block list first, and then the Global exclusion list etc. I suggest you Whitelisting the IP to see if it works fine since the send is blocked by the third party Internet Blacklist group. However, since the sender is flagged in Blacklist for some reason, I think you can advice them to delist themselves from the blacklist following the requirement of that third party group. Which is better for the security.

    Thanks,

    Alison

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  1. Anonymous
    2017-05-16T03:41:03+00:00

    Hi Exchange_Engineer_4L,

    Do you have any more questions?

    Best Regards,

    Alison

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  2. Anonymous
    2017-05-12T17:31:46+00:00

    Alison Wang:

      I apologize, I should have been a bit more descriptive in my problem statement. The Blacklist is an Internet based Blacklist, not a blacklist within our tenant. The sender's relay has been flagged by a third party Internet Blacklist group and in looking at the headers from a messages sent from the sending organization and running it through MXTOOLSBOX analyzer that is how we discovered the blacklist issue. So, my real question is, would whitelisting the IP address of the Blacklisted relay be the best option or would whitelisting the sender's email address be the better course of action? If we whitelist the email address only would the fact that the relay is still showing as blacklisted stop the emails from getting through or would it be enough? Thank you for your help.

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  3. Anonymous
    2017-05-12T17:00:22+00:00

    Hi Exchange_Engineer_4L,

    If another organization's IP is blocked under the conncetion filter setting of your tenant, the mail will be blocked no matter the specific sender is added to the recipient's allow list or not. I suggest you add the IP in the whitelist of your tenant first.

    Thanks,

    Alison

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