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

Customers currently using the Connect Application are advised to complete their onboarding setup as soon as possible, as the Connect Application is scheduled to be discontinued on the 31st of January, 2024.

This article contains information on configuring inbound email for On-Premise/Hybrid Exchanges using the Connect Application, including environment setup, domain routing, and delivery route specification.

This guide is only for customers using the Connect Application and describes the requirements and preparations to configure the Inbound Email for On-Premise / Hybrid Exchanges with the Connect Application.
This applies to:

• • • New clients are connecting with Mimecast using the Connect Application to an On-Premise or Hybrid Exchange.

This does NOT apply to:

• • • Customers only using Microsoft 365 should refer to the Setting Up Your Email (Microsoft 365) page instead.
    • Customers not using the Connect Application should click here.

Overview

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

• • • Configuring your environment to accept email from Mimecast.
    • Selecting your domains to route.
    • Specifying the inbound delivery route.
    • Verifying the connection.

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 have created an "Everyone To Internal" delivery route policy using the Mimecast 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 disrupting 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 emails 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 to your validated domains. Your primary domain is displayed, but if you have validated other domains, emails 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:

   Field / Option	Description
   Hostname/IP	Enter the hostname or IP of the main delivery route to be used for inbound email.
   Port	Specify the port used for SMTP email delivery. The default port is 25.

2. Specify an Alternate Route as follows:

   Field / Option	Description
   Hostname/IP	Enter the hostname or IP of the alternate delivery route to be used for inbound email.
   Port	Specify 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 is listed under Routed Email Domains.

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 Connect Application - Updating Your MX Records.

See Also...

• • • Connect - Setting Up Your Inbound Email