Why does Office 365 hosted exchange use 25.x.x.x IP addresses?

Discussion in 'Office 365' started by popowich, May 6, 2015.

  1. popowich

    popowich EQ Forum Admin Staff Member

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    It was recently reported that users of the Office 365 exchange service are seeing 25.x.x.x IP addresses in their full email headers.

    As far as I can tell, these addresses may be used "internally" by Microsoft, but are not used for relaying email to other service providers.

    I came to that conclusion because the IP addresses I checked from the full headers of emails do not have a sender score, for example:

    Lookup for 25.161.223.18 - SenderScore.org

    The lack of PTR records or mention of Microsoft in a whois lookup is interesting:

    OrgName: RIPE Network Coordination Centre
    OrgId: RIPE
    Address: P.O. Box 10096
    City: Amsterdam
    StateProv:
    PostalCode: 1001EB
    Country: NL
    RegDate:
    Updated: 2013-07-29

    Update: A Microsoft rep commented that this address range is used for Microsoft Exchange Online Protection (EOP) service.
     


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