Configuring Inbound Delivery Routing for Microsoft 365 explained
Dear Primary Contact,
This graphic illustrates the steps required to connect your infrastructure to Mimecast. If you'd like more information click the image to visit our knowledge base. Green indicates your current step, while gray indicates completed steps.
Next Steps
1. Ensure that your mail server is open to receive email from the Mimecast data center IP ranges.
2. Test your delivery routes in the Administration Console before making any DNS changes. This confirms Mimecast can correctly send mail to your server. If you need to make any changes to your delivery routing (i.e. you have multiple servers, backup hosts, etc.) please review your delivery routing configuration.
Note - If you plan to deliver inbound email to Office 365, we recommend you create a connection filter based on the Mimecast data center IP ranges to ensure that inbound email is not spam scanned or quarantined by Office 365 when it is delivered by Mimecast
3. Ask your DNS service provider to change the MX records for your domain(s) so that they point to the following Mimecast services:
-MX priority 10 us-smtp-o365-outbound-1.mimecast.com
-MX priority 10 us-smtp-o365-outbound-2.mimecast.com
It's very important to ensure that you only associate two Mimecast MX records with your domains. If you include extra MX records which still accept email, these can be exploited by spammers and viruses as a soft backdoor. Similarly, if you do not remove old host names that are no longer active, it could result in legitimate emails being bounced if they route via the old MX records.
4. Log in to the Administration Console and use our Accepted Email menu item, or 'Tracking' features (within the Gateway menu) to confirm that your inbound mail is being routed via Mimecast. Mimecast makes it easy to trace the delivery of messages and investigate potential mail flow issues:
-Guidelines for troubleshooting mail delivery.
-General information on gateway tracking.
-Confirming receipt and delivery times.
5. Once your inbound email is routing via Mimecast, messages may be held by our spam scanning policies and users will be notified via digest notifications. As a result we recommend you review your digest configuration and ensure your users are aware of how they should interact with digest notifications.
Once our systems detect inbound traffic on your account, we'll send you the details for your next step.
Please respond to this email if you have any questions about this step.
Kind regards,
Mimecast North America, Inc.
480 Pleasant Street
Watertown, MA 02472
Carlos Rios
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