Whitelisting Dune Security in Mimecast

This guide walks you through configuring key Mimecast policies to ensure seamless email security and delivery, with a focus on integrating Dune Security's Email Exchange via a Partner Receive Connector for optimal performance.

IMPORTANT: Instead of allowlisting Mimecast, we highly recommend to set up a Partner Receive Connector between Dune Security and your Email Exchange for optimal delivery.

Mimecast Policy Basics(this helps with filling in emails_from and emails_to fields): https://community.mimecast.com/s/article/email-security-cloud-gateway-policy-basics

MimeCast Anti-Spoofing Policy

For more information, see Mimecast’s guide on Setting Anti-Spoofing Policy

Step 1: Access the Administration Console

1. Log in to your Mimecast Administration Console.
2. Click on the Administration toolbar.

Step 2: Navigate to Policies

1. Select Gateway from the menu.
2. Choose Policies.

Step 3: Configure Anti-Spoofing Policy

1. Click on Anti-Spoofing from the list of displayed policies.
2. Select New Policy.

Step 4: Set Policy Options

1. Customize the policy settings under:
   1. Options: Define your preferred settings.
   2. Emails From: Specify the sources of incoming emails.
   3. Emails To: Determine the target recipients for the policy.
   4. Validity: Set the timeframe for the policy's application.
2. Click Save to apply your settings.

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2. Excerpt from Mimecast

Step 5: Apply Policy Override and Set Source IP

1. Check the Policy Override box to allow exceptions.
2. In the Source IP Ranges field, enter the sender IP address:
   • Sender IP: 52.201.210.35

Step 6: Save the Policy

1. Click Save to finalize and apply the policy settings

Permitted Senders Policy-

Important: Do not edit your default Permitted Sender policy. A new one must be created.

For more information, see Mimecast’s guide on Setting a Permitted Senders Policy

Step 1: Access the Administration Console

1. Log in to your Mimecast Administration Console.
2. Click on the Administration toolbar.

Step 2: Navigate to Permitted Senders Policy

1. Select Gateway from the menu.
2. Choose Policies.
3. Click on Permitted Senders from the list of displayed policies.

Step 3: Create a New Permitted Senders Policy

1. Click New Policy.

Step 4: Configure Policy Settings

1. Customize the policy settings under the following sections:
   • Options: Adjust settings based on your requirements.
   • Emails From: Specify the allowed senders.
   • Emails To: Define the intended recipients.
   • Validity: Set the duration for the policy's application.

Step 5: Save the Policy

1. Click Save to apply your new Permitted Senders policy.

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Step 6: Finalize the Permitted Senders Policy

1. In the Permit Sender Policy, select Permit Sender.
2. Check the Policy Override box to enable exceptions.
3. In the Source IP Ranges field, enter the following sender IP address:
   • Sender IP: 52.201.210.35

Step 7: Save the Policy

1. Click Save to apply and activate the Permitted Senders policy.

URL Protection Bypass Policy-

For more information, see Mimecast’s guide on Setting a URL Bypass Policies

Step 1: Access the Administration Console

1. Log in to your Mimecast Administration Console.
2. Click on the Administration toolbar.

Step 2: Navigate to URL Protection Bypass Policy

1. Select Gateway from the menu.
2. Choose Policies.
3. Click on URL Protection Bypass from the list of displayed policies.

Step 3: Create a New URL Protection Bypass Policy

1. Click New Policy.

Step 4: Configure Policy Settings

1. Adjust the policy settings under the following sections:
   • Options: Choose the appropriate options for the policy.
   • Emails From: Specify the sources to be bypassed.
   • Emails To: Indicate the target recipients for bypassing URL protection.
   • Validity: Set the time period for which the policy will be active.

Step 5: Save the Policy

1. Click Save to apply your new URL Protection Bypass policy.

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Step 6: Apply Policy Override and Set Source IP

1. Check the Policy Override box to allow exceptions.
2. In the Source IP Ranges field, enter the sender IP address:
   • Sender IP: 52.201.210.35

Step 7: Save the Policy

1. Click Save to finalize and activate the URL Protection Bypass policy.

Impersonation Protection Bypass Policy-

For more information, see Mimecast’s guide on Setting up Impersonation Protection Bypass Policy

Step 1: Access the Administration Console

1. Log in to your Mimecast Administration Console.
2. Click on the Administration toolbar.

Step 2: Navigate to Impersonation Protection Bypass Policy

1. Select Gateway from the menu.
2. Choose Policies.
3. Click on Impersonation Protection Bypass from the list of displayed policies.

Step 3: Create a New Impersonation Protection Bypass Policy

1. Click New Policy.

Step 4: Configure Policy Settings

1. Adjust the policy settings under the following sections:
   • Options: Set the appropriate options for the policy.
   • Emails From: Specify the sources to be bypassed.
   • Emails To: Indicate the intended recipients.
   • Validity: Set the time period for which the policy will be active.

Step 5: Apply Policy Override and Set Source IP

1. Check the Policy Override box to allow exceptions.
2. In the Source IP Ranges field, enter the sender IP address:
   • Sender IP: 52.201.210.35

Step 6: Save the Policy

1. Click Save to finalize and activate the Impersonation Protection Bypass policy.

 

Preventing Mimecast from Rewriting Phishing links-

Mimecast’s guide on adding a domain or URL to a block or allow list: https://community.mimecast.com/s/article/email-security-cloud-gateway-ttp-url-protect-managed-urls

Part 1: Configuring Permitted URLs

If you want to prevent Mimecast from re-writing the links in the phishing tests you send, you can do this by adding Dune Security's domains as Permitted URLs in Mimecast.

1. Log in to your Mimecast Administration Console.
2. Click on the Administration toolbar.
3. Navigate to Gateway > Policies.
4. Select Permitted URLs from the list.
5. Add the Dune Security domains to ensure the links remain intact during phishing simulations.

Part 2: Configuring Attachment Protection Bypass Policy

Step 1: Access the Administration Console

1. Log in to your Mimecast Administration Console.
2. Click on the Administration toolbar.

Step 2: Navigate to Attachment Protection Bypass Policy

1. Select Gateway from the menu.
2. Choose Policies.
3. Click on Attachment Protection Bypass from the list of displayed policies.

Step 3: Create a New Attachment Protection Bypass Policy

1. Click New Policy.

Step 4: Configure Policy Settings

1. Adjust the policy settings under the following sections:
   • Options: Set the appropriate options for the policy.
   • Emails From: Specify the sources to be bypassed.
   • Emails To: Define the intended recipients.
   • Validity: Set the duration for which the policy will be active.

For more detailed guidance on configuring this policy, refer to Mimecast's official guide on Setting up Attachment Bypass Policy.

Step 5: Apply Policy Override and Set Source IP

1. Check the Policy Override box.
2. In the Source IP Ranges field, enter the sender IP address:
   • Sender IP: 52.201.210.35

Step 6: Save the Policy

Click Save to finalize and activate the Attachment Protection Bypass policy.