Office 365 SPAM bounce back issues


Have a client that moved to Office 365 a couple months ago.  In last 10 days having issue with senders getting a bounce back stating they are on a SPamHaus list.  When you look up their sending IP address in the SpamHaus database, it is not listed.

Any thoughts?
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ClearBlueTechnologiesConnect With a Mentor Author Commented:
It turned out to be the original sender IP address field on outbound emails.  We set O365 to strip that field on outbound emails.  This fixed the problem.
Vasil Michev (MVP)Commented:
First of all, make sure that those are legitimate NDRs and not some sort of NDR spam.

For checking, you need to check the Exchange server IPs, but even if you confirm a match, there's almost nothing you can do. Office 365 support cannot and will not assist you with that, it's responsibility (and a freedom of choice) for the recipient to decide which emails to block. In most cases, they surely do not want to block the entire O365 service, so simply emailing them via a different address and explaining the situation should help you sort it out. Just ask them to add your domains to their safe senders list and if possible, to alert their admins of the situation.

Also, make sure that you have added the SPF record for your domain, it will help prevent messages sent from the cloud service being incorrectly identified as spam.
ClearBlueTechnologiesAuthor Commented:
Figured it out on our own.
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