Policies - Secure Receipt Policy Configuration

This article explains how to configure the Secure Receipt policy.
See Secure Delivery Configuration for details on configuring Secure Delivery.

When configuring route-based TLS, the following policies are required to ensure the entire transmission is encrypted:

• Secure Receipt policy: This encrypts data between the sending mail server and us (i.e., how we receive a message).
• Secure Delivery policy: This encrypts data between Mimecast and the destination mail server (i.e., how we deliver a message).

TLS technology protects confidentiality and data integrity by encrypting connections between servers and transmitting messages through a secure tunnel.
It uses SMTP over an SSL-encrypted tunnel and requires an installed third-party certificate at each end of the tunnel. See the Self-signed certificates section below for further information. We support connections using TLS 1.2 and TLS 1.3 for AES-256, MD5, and AnonDHE.

Self-Signed Certificates

To configure and use TLS, each mail server involved in the sending and receipt of a message must have an SSL certificate from a public root certificate authority installed and configured. By default, TLS connections take place over port 25.

For Secure Receipt policies, we act as the server. The client application connects to us and checks the server certificate to see if it is acceptable. Typically, it would be, and the connection is established. If a self-signed certificate is used by the client, the connection attempt will fail.

Mimecast has a configuration option that allows a connection to be established. In this scenario, we act as the client, and the customer application acts as the server. We will then verify the certificate.

Configuring a Secure Receipt Policy

You can configure a Secure Receipt policy by using the following steps:

1. Log in to the Mimecast Administration Console.
2. Navigate to Policies | Gateway Policies.
3. Click on Secure Receipt.
4. Either select the following:

• • Policy to be changed.
  • New Policy button to create a policy.

5. Complete the Options section as required:

Option	Description
Policy Narrative	Provide a description of the policy to allow you to easily identify it in the future.
Select Option	Select one of the following values from the drop-down list: Default: Uses Opportunistic TLS as described below. Enforced TLS: The connection must be encrypted. If encryption can't be negotiated, Mimecast will not accept the message. Opportunistic TLS: TLS is always attempted first when sending a message, but if the remote mail server is not accepted, the message is received using standard SMTP.

6. Complete the Emails From and Emails To sections as required:

Field / Option	Description
Addresses Based On	Specify the email address characteristics on which the policy is based. This option is only available in the Emails From section: The Return Address: This default setting applies the policy to the SMTP address match based on the message's envelope or true address (i.e., the address used during SMTP transmission).
Applies From / To	Specify the Sender characteristics on which the policy is based. For multiple policies, you should apply them from the most specific to the least specific. The options are: Everyone: Includes all email users (i.e., internal and external). This option is only available in the Emails From section. Internal Address: Includes only internal organization addresses. External Address: Includes only external organization addresses. This option is only available in the Emails From section. Email Domain: This enables you to specify a domain name to which this policy is applied. The domain name is entered in the Specifically field. Address Groups: This enables you to specify a directory or local group. If this option is selected, click the Lookup button to select a group from the Profile Group field. Once a group has been selected, you can click on the Show Location field to display the group's path. Address Attributes: This enables you to specify a predefined Attribute. The attribute is selected from the Where Attribute drop-down list. Once the Attribute is specified, an attribute value must be entered in the Is Equal To field. This can only be used if attributes have been configured for user accounts. Individual Email Address: This enables you to specify an SMTP address. The email address is entered in the Specifically field.

7. Complete the Validity section as required:

Field / Option	Description
Enable / Disable	Use this to enable (default) or disable a policy. If a date range has been specified, the policy will automatically be disabled when the end of the configured date range is reached.
Set Policy as Perpetual	If the policy's date range has no end date, this field displays Always On, meaning that the policy never expires.
Date Range	Use this field to specify the policy's start and/or end date. If the Eternal option is selected, no date is required.
Policy Override	This overrides the default order in which policies are applied. If there are multiple applicable policies, this policy is applied first unless more specific policies of the same type are configured with an override.
Bi-Directional	If selected, the policy is applied when the policy's recipient is the sender and the sender is the recipient.
Source IP Ranges (n.n.n.n/x)	Enter any required Source IP Ranges for the policy. These only apply if the source IP address used to transmit the message data falls inside or matches the range(s) configured. IP ranges should be entered in CIDR notation.

8. Click on the Save and Exit button.

To verify if TLS is being applied as expected once your policy is configured, send a test email and check the receipt/delivery view of the message.

See Also...

• • • Secure Delivery Configuration.