Policies - Configuring Email Size Limits Policies

This article provides information on configuring Mimecast Email Size Limits policies to manage inbound and outbound email sizes, conserve storage, and enforce organizational limits. This includes steps for setup, usage considerations, and policy customization.

Email Size Limits policies allow you to set limits for both inbound and outbound mail, including the cumulative size of a message and its attachments. Any messages exceeding the specified size are rejected because the Message exceeds the email size limit. This policy is useful to:

• Conserve storage in your company's internal environment.
• Enforce limits to the size of emails allowed in and out of your organization.

If you have Large File Send as part of your Mimecast subscription, this can be used to send messages that would otherwise not be sent because of an Email Size Limit policy.

Usage Considerations

Consider the following before creating a policy:

• A default policy is created with your Mimecast account. The threshold set in the policy depends on which Gateway version your account uses. The current Gateway is 200 MB.
• Size restrictions on your internal mail server should match the limit on messages allowed through Mimecast. For example, if an inbound limit on Mimecast is applied at 20MB and the mail server is restricted to 10MB, we will accept an inbound email between 10MB and 20MB, but we won't deliver it to your infrastructure.
• It is beneficial to have an understanding of the different components that make up a message. See the Email Size and Attachment Policies page for details.
• The threshold must be set to the maximum transmission size you'd like us to accept. This functions like the Maximum Message Size threshold on a Microsoft Exchange Server.
• The transmission and content encoding can add significantly to the total size of a message.
• The Email Size Limits policy overrules the Attachment Block on Size and Configuring Attachment Hold on Size policies.

Configuring an Email Size Limits Policy

To configure an Email Size Limits policy:

1. Log in to the Mimecast Administration Console.
2. Navigate to the Policies | Gateway Policies menu item.
3. Click on Email Size Limits.
4. Select either the following:

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

5.   Complete the Options section as required:

Field / Option	Description
Policy Narrative	Describe the policy to allow you to identify it easily in the future.
Maximum Email Size (KB)	Specify the maximum size of the email in kilobytes.

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

Field / Option	Description
Addresses Based On	Specify the email address characteristics that the policy is based on. 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 that the policy is based on. You should apply multiple policies, from the most 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, click 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 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.

See Also...

• • • Email Size and Attachment Policies
    • The Gateway Policy Editor