Connect Process: Setting up Your Outbound Email

Document created by user.oxriBaJeN4 Employee on Sep 21, 2015Last modified by user.oxriBaJeN4 Employee on Apr 2, 2019
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Once your Mimecast account has been created, your Technical Point of Contact (TPOC) should log onto the account to confirm they can access it. If this is successful, your email server can be configured to route outbound emails through Mimecast. This requires that your:

  • Public IP addresses are added to Mimecast's authorized outbounds. The Connect Team will configure these based on the information received in the Request for Information (RFI).
  • Firewall is configured to allow access to Mimecast Data Center IP Ranges for SMTP port 25. See the Global Data Centers page for more information.

    This step may not be applicable on Hosted Exchange (HEX) and Office 365 implementations. See the relevant section below for further detail.

  • Email server or cloud service must be configured to deliver emails to Mimecast. See the relevant section below to display the configuration steps.

If you currently use SPF records for your domains, ensure you include a comprehensive list of Mimecast outbound IP addresses in your DNS SPF record. For more information, see the "Implementing SPF for Outbound Email Delivery" section of the Configuring DNS Authentication Definitions and Policies page.

Office 365 Environments


For detailed instructions, see the Office 365: Configuring Outbound Delivery Routing page.


On Premises Environments


Routing your outbound mail to Mimecast in Exchange is accomplished through the creation of a send connector. We provide two unique smart hosts per region to ensure 100% availability. We will email these to your Technical Point of Contact as part of the Connect Process. The Mimecast Gateway page also provides this information. Both hostnames should be used to ensure round robin traffic and provide a failover.


For more information on how to configure SMTP connectors, view the relevant article below:



If you utilize non-static public IP addresses, refer to the Configure SMTP Authentication on Exchange page.


You can monitor your live outbound traffic being logged by clicking the Administration | Message Center | Accepted Messages menu item in the Administration Console. This displays all emails being processed by Mimecast.


Hosted Exchange (HEX) Environments


To set up your outbound email, forward our outbound routing instructions to your HEX provider to make the required changes. Ensure they consider the following when setting up your outbound email:

  • In a multi-tenanted HEX environment, there are normally a number of customers on one server sending email outbound via a single Exchange send connector. If one of the customers on the HEX platform implements Mimecast, their outbound email must be separated from the rest of the clients on that HEX platform. All outbound email should then be sent to Mimecast for delivery, as opposed to being sent to the internet using the standard Exchange send connector. This is called Sender Address Based Routing, which is not a standard Exchange function. To implement Sender Address Based Routing, either a third party tool or additional hardware is required to send outbound email directly to Mimecast.


G Suite Environments


To prepare your outbound G Suite hostname:

  1. Log on to the Google Admin Console.
  2. Navigate to Apps | G Suite | Gmail | Advanced Settings.
  3. Click on the Hosts button.
  4. Click on the Add Route button.
  5. Enter a Route Name (e.g. Mimecast Outbound Host).
  6. Select Multiple Host and enter the Mimecast Outbound Hostnames for your Mimecast region. Both must be marked as primary. See the "Outbound Send Connectors section of the Mimecast Gateway page for full details.
  7. Click on the Save button.
  8. Click on the Add Route button.
  9. Enter a Route Name (e.g. Internal Sending Host).
  10. Select Multiple Host and enter the Google Apps MX Records (ASPMX.L.GOOGLE.COM. and ALT1.ASPMX.L.GOOGLE.COM).
  11. Click on the Save button.


To configure routing rules:

  1. Click on the General Settings tab.
  2. Navigate to the Routing section.
  3. Click on the Configure button.
  4. Select the Outbound option in the "Messages to Affect" section.
  5. Select the Change Route option in the Route section.
  6. Select the Route Name created in step 5 of the "Preparing Your Outbound Hostname" section.
  7. Click on the Add Setting button.
  8. Click on the Add Another button.
  9. Select the Internal | Sending option in the "Messages to Affect" section.
  10. Select the Change Route option in the Route section.
  11. Select the Route Name created in step 9 of the "Preparing Your Outbound Hostname" section.
  12. Click on the Show Options link.
  13. Select the Groups option 
  14. Click on the Add Setting button.
  15. Click on the Save button.
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