This article contains information on configuring Mimecast Delivery Routing policies to control email delivery routes, override MX records, and manage traffic flow, including setup, testing, and considerations for alternate routes and SMTP authentication.
Delivery Routing policies allow email delivery to a specific server based on a domain, group, attribute, or individual address. They determine the route used for inbound email delivery to your framework and contain all the details of the delivery destination (e.g., the hostname or IP Address of the email server). This policy can also be used to override MX (mail exchange) records for outbound delivery.
Considerations
Consider the following before configuring a definition or policy:
- By default, outbound mail is delivered to the recipient using available MX records. If an outbound Delivery Route policy has been configured, this overrides the default MX record.
- Delivery routes require the specific route to be defined in a definition and a policy to determine traffic flow. Alternate routes can be created, which enable a fail-over option should a customer's primary route be unavailable.
- If multiple similar routes (the FROM and TO variables are the same) are configured, this results in a round-robin (random selection) of these routes. This is also useful for balancing mail server load.
- If route information is no longer valid, it is possible to change the delivery route for a message by either:
- Adjusting the delivery route definition, taking care not to change the description field.
- Removing the original policy that applied to a message and applying a new policy with an associated definition. The Recalculate button in the delivery queue forces us to review the current policy that applies to the message awaiting delivery. This feature is only available to customers utilizing our latest Gateway.
Configuring a Delivery Route Definition
To configure a Delivery Route definition:
- Log in to the Mimecast Administration Console.
- Navigate to Policies | Gateway Policies | Delivery Routing (Definitions Button).
- Either click on the:
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- Definition to be changed.
- New Route Definition button to create a definition.
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- Complete the Route Properties section as follows:
| Field/ Option | Description |
|---|---|
| Description | Give the definition a description.
Do not change the description once it has been applied to a delivery routing policy. Doing so results in delivery issues for any messages currently tied to that route. If the address for one of the routes changes, you can update the information. |
| Hostname | Enter a Public IP address or a publicly resolvable DNS name. This IP address/hostname needs to be accessible from the internet for us to use it as a delivery route. |
| Port | Specify a port number. The default value is TCP 25 (SMTP) unless other specific requirements exist. |
| Pause | If your mail server is down for planned or unplanned reasons, we continue to accept inbound mail. Messages are held in the Delivery Queue, and we will attempt to deliver to the mail server based on the email delivery schedule. Once your mail server is back, you can wait for the message to be delivered according to the schedule or manually retry the messages in your delivery queue. We will attempt to deliver mail for up to 30 attempts over 6320 minutes (four days). If the outage is more prolonged than this, we will issue a Non-Delivery Report (NDR) to the email sender. If you're expecting an outage for longer than four days, it is possible to Pause inbound mail delivery for an indefinite period. We can do this by using this option or your Mimecast Account Settings.
Mail reaching a month or more since being accepted under the paused condition will not be delivered once the pause is removed. |
| Start Date | If the Pause option is selected, specify a date you want the delivery of inbound mail to be paused. |
| Expiry Date | If the Pause option is selected, specify a date you want the delivery of inbound mail to stop being paused. You can use the Set to Eternal button to set the date to eternity. You can also use the Expire Now button to end the pause immediately. |
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Complete the Alternate Routes section as follows:
| Field/ Option | Description |
|---|---|
| Alternate Route | We will always attempt to deliver messages to the primary route specified in the Host Name field. If the Primary route is unavailable, Alternative routes can also be defined. We will try the alternative routes in the order specified. Use the drop-down menu to select other delivery route definitions that have been saved. |
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Complete the Optional SMTP Authentication Settings as follows: We recommend you select the mechanism that your email server supports natively first. Then, if the selected authentication mechanism is unsuccessful, the next in the list is attempted.
| Field/ Option | Description |
| Enable SMTP Authentication |
Some organizations require SMTP authentication before they accept messages to their servers, which helps to increase the security measures for safe delivery. The following authentication mechanisms are supported:
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| Authentication Mechanisms | The available mechanisms are listed on the left, with the selected mechanisms on the right. Select a mechanism from a list and use the Add or Remove button to add it to the required list. Multiple mechanisms can be enabled and utilized in the list's order. Select a mechanism from a list and use the Up or Down button to change their order of preference. |
| Username | Specify the domain's username. |
| Password | Specify the domain's password. |
| Domain | Specify the domain. |
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Click on the Save and Exit button.
Removing a Delivery Route Definition
Consider the following before removing a Delivery Route definition:
- You cannot remove a delivery route if:
- A policy references the route.
- A message has been processed by us but hasn't been archived (e.g., a held, accepted, or delayed message).
- The definition is considered in use until all messages that apply to that Delivery Route policy have been delivered. If an attempt is made to remove the definition, the following error is displayed:
"Unable to Delete - Definition is still in use by non-archived items. Please consider disabling the Policy for now so that you can delete it at a later stage."
To remove an existing Delivery Route:
- Right-click on a Route in the list.
- Click on the Remove Route menu item.
Configuring a Delivery Route Policy
To configure a Delivery Route policy:
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Log in to the Mimecast Administration Console.
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Navigate to Policies | Delivery Policies | Delivery Routing.
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Either click on the:
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- Policy to be changed.
- New Policy button to create a policy.
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Complete the Options section as required:
| Field/ Option | Description |
|---|---|
| Policy Narrative | Describe the policy to allow you to identify it in the future quickly. |
| Select Route | Select a delivery route definition for the policy. |
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Complete the remainder of the policy as necessary; refer to the Policy Basics: From / To / Validity KB article if needed.
Recommended scoping of the Delivery Route policy is as below:
From [Everyone] to [Internal].
Testing Delivery Routes
We provide the ability to test connectivity to your mail server, ensuring that messages are successfully delivered via the configured Delivery Route. To test Delivery Routes:
- Configure the Delivery Route Definition and Policy as described above.
- Next, click on the Test Connection button in the toolbar.
- Monitor inbound mail using the Delivery Queue to ensure that delivery is successful.
- Once the mail has been delivered, the Delivery Route used for specific messages can be checked using the receipt/delivery view in either:
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- Message Center | Accepted Message.
- Archive | Archive Search.
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