Policies - Attachment Link on Size

This article explains how Attachment Link on Size policies works. Inbound and outbound mail attachment sizes can be limited with this policy. The recipient receives the original message with notifications rather than being denied access to the attachment. You can download attachments to your local desktop rather than having them delivered to the mail server. As a result, administrators can maintain end-user needs while managing bandwidth and storage challenges.

Usage Considerations

Consider the following when configuring a policy:

• Whilst end users are able to download stripped attachments directly to their local desktop, the attachments are also held in the administration on-hold queue. Administrators only have the ability to release these attachments into the Exchange Server environment. See the Releasing Emails and Attachments page for further details.
• Both the Email Size Limits and Attachment Block on Size policies overrule this policy.
• Users can choose to strip and link attachments over 1 MB in size using Mimecast for Outlook.
• The link to download attachments is valid as long as a message is in your archive (e.g., your maximum retention period).

Configuring an Attachment Link on Size Policy

To configure an Attachment Link on Size policy:

1. Log in to the Mimecast Administration Console.
2. Click on the Policies | Gateway Policies menu item.
3. Click on Attachment Link On Size.
4. Either select the:

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

5.   Complete the Options section as required:

Field / Option	Description
Policy Narrative	Provide a description of the policy to allow you to easily identify it in the future.
Link Attachments Larger Than (KB)	Specify a value in kilobytes for the maximum file size of all attachments in a message. Any attachments that exceed this limit are not delivered with the message. For example, if 1000 KB is specified and a message has two attachments of 550 KB each, both attachments are replaced with links. Attachments under 50 KB in size are automatically ignored.

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 options are: The Return Address (Mail Envelope From): 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). The Message From Address (Message Header From): Applies the policy based on the masked address used in the message's header. Both: Applies the policy based on either the Mail Envelope From or the Message Header From, whichever matches. If both match the specified value, the Message Header From is used.
Applies From / To	Specify the Sender characteristics that the policy is based on. 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: Enables you to specify a domain name to which this policy is applied. The domain name is entered in the Specifically field. Address Groups: Enables you to specify a directory or local group. If this option is selected, click on 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: 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: 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 a start and/or end date for the policy. 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