<div>
First of all, make sure that those are legitimate NDRs and not some sort of NDR spam. <br />
<br />
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.<br />
<br />
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.
</div>


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.

<div>
<div class="content wysiwyg-content">
All,<br />
<br />
Have a client that moved to Office 365 a couple months ago. &nbsp;In last 10 days having issue with senders getting a bounce back stating they are on a SPamHaus list. &nbsp;When you look up their sending IP address in the SpamHaus database, it is not listed.<br />
<br />
Any thoughts?
</div>
</div>


All,

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?

Office 365 SPAM bounce back issues

Office 365 is a group of software plus services subscriptions that provides productivity software and related services to its subscribers. Office 365 allows the use of Microsoft Office apps on Windows and OS X, provides storage space on Microsoft's cloud storage service OneDrive, and grants 60 Skype minutes per month. Office 365 includes e-mail and social networking services through hosted versions of Exchange Server, Skype for Business Server, SharePoint and Office Online, integration with Yammer, as well as access to the Office software. All of Office 365's components can be managed and configured through an online portal; users can be added manually, imported from a CSV file, or Office 365 can be set up for single sign-on with a local Active Directory using Active Directory Federation Services.

Microsoft 365

Exchange is the server side of a collaborative application product that is part of the Microsoft Server infrastructure. Exchange's major features include email, calendaring, contacts and tasks, support for mobile and web-based access to information, and support for data storage.

Exchange

Various techniques are used to prevent email spam (unsolicited bulk email). No technique is a complete solution to the spam problem, and each has trade-offs between incorrectly rejecting legitimate email (false positives) vs. not rejecting all spam (false negatives) - and the associated costs in time and effort. Anti-spam techniques can be broken into four broad categories: those that require actions by individuals, those that can be automated by email administrators, those that can be automated by email senders and those employed by researchers and law enforcement officials.