Connect Application: Preparing for Inbound Email (On-Premise / Hybrid Exchanges)

Document created by user.oxriBaJeN4 Employee on Apr 14, 2016Last modified by user.Yo2IBgvWqr on Feb 7, 2018
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Connect_Routing_Inbound.pngApplies To...


  • New clients connecting with Mimecast using the Connect Application on an On Premise or Hybrid Exchange. Users of Office 365 should refer to the Setting Up Your Email (Office 365) page. If you are not using the Connect Application, click here.
  • Customers using Mimecast for email security.




To prepare your Exchange environment to accept inbound emails routed to us, you'll need to complete the following tasks:

  • Configure your Exchange environment to accept inbound email from us.
  • Select additional domains to route to the same destination as your primary domain.
  • Specify the inbound delivery route.
  • Route your other domains.


To prepare for inbound email:

  1. Navigate to the Gateway | Prepare for Inbound Email menu item. 
  2. Click the Start button. 
  3. Configure your Exchange to accept inbound emails from us.

If you’ve created an "Everyone To Internal" delivery route policy using the Administration Console, an option is presented to use it, but for granularity we recommend you create new routes using the Connect App.

Configuring Your Environment to Accept Email From Mimecast


To avoid disruption to your email flow, you must set us up as your trusted email source. This is achieved by ensuring your environment is configured to receive inbound mail from our data centers, as we process your inbound email before delivering it to your Exchange. Emails may be blocked unless this is completed successfully.


To allow your environment to accept email from us:

  1. Configure your firewall to accept SMTP traffic from our Inbound IP Ranges. These are displayed in the Connect application.
  2. Click the Next button.
  3. Route your inbound emails to the domains displayed in the application (see below).


Selecting Your Domains to Route



This step lets us know where to deliver emails that are addressed to your validated domains. Your primary domain is displayed, but if you have validated other domains, email destined for these can also be routed to the same destination.


To route email to other domains:

  1. Select the domains to be routed. Your primary domain is automatically selected.
  2. Select any Additional Domains by either clicking the:
    • Check Box to the left of the domain (see the image on the right).
    • Select All link.
  3. Click the Next button.
  4. Specify the domain’s inbound email delivery route (see below).


Specifying the Inbound Delivery Route


To specify the delivery routes of your domains:

  1. Complete the dialog for the Delivery Route as follows:
    Hostname/IPEnter the hostname or IP of the main delivery route to be used for inbound email.
    PortSpecify the port used for SMTP email delivery. The default port is 25.
  2. Specify an Alternate Route as follows:
    Hostname/IPEnter the hostname or IP of the alternate delivery route to be used for inbound email.
    PortSpecify the port used for SMTP email delivery. The default port is 25.
    Although not required, we strongly recommend you provide an alternative route to ensure there is no break in your service.
  3. Click the Verify Route buttons. A Test Inbound Host popup box displays.
  4. Enter a valid Internal Email Address to verify your inbound route, and click the Test button. 
  5. If the route is configured successfully, a message will confirm your host can receive mail from Mimecast.
  6. Click the Finish button. A summary page displays your successfully routed email domains.

Once you've finished verifying the domain delivery routes, the primary IP address, CIDR, or hostname being used by each validated domain are listed under Routed Email Domains.

Domain Delivery Route


Verifying the Connection


We'll verify the Exchange mail flow connector by monitoring inbound email traffic. Additionally, a delivery and routing definition policy is automatically created for each of your domains.

Inbound email is not routed via our gateway until you Modify your MX records.