The Attachment Management feature allows system administrators to strip attachments from email messages at the gateway and store them in Netmail Store (or a Netmail Store emulator; see note below), helping reduce storage bloat on the Exchange server. Each stripped attachment is replaced with an HTTP link that points to the original attachment in the storage repository. As such, it is possible to manage email mailbox sizes by removing storage-intensive attachments before they ever enter Exchange, all the while keeping the attachments accessible to end users.
The Attachment Management Policy was designed to streamline the configuration of Netmail Detach, in that the configuration parameters are the same as those found in the Netmail Archive Attachment Management Agent. Previously, the stripping of attachments was performed through Attachment Blocking policies. However, Attachment Blocking polices relied on long, cumbersome lists of forbidden file extensions that may not have necessarily been complete. With the Attachment Management policy, all attachments are stripped, regardless of their file type. This means that no attachments are left behind.
This page provides step-by-step instructions on how to create an Attachment Management policy. If you have already created your Attachment Management policy or are using a custom policy, then see Configuring Domains, Groups and Users to learn how to apply policies and overrides to different levels: per domain, per group or per user.
To create your Attachment Management policy, choose Secure > Policies > Attachment Management. On the Details tab, click Create Attachment Management Policy. Enter a name for your new Attachment Management policy, and then click Create. Your new policy now appears in the tree menu on the left-hand side of the Netmail Administration Console. Click the name of the Attachment Management policy you have just created to configure it. By default, the Actions tab is displayed.
Note: Netmail does not strip embedded attachments.
Important: Netmail Store is required to implement Attachment Management. If, however, an existing storage system (e.g., NAS or SAN) is already in place and has a significant amount of free storage available, Netmail Store Emulator can be configured. Netmail Store Emulator behaves like Netmail Store but runs on the file system and provides Netmail with HTTP access to your storage device.
Setting Attachment Management Policy Criteria
Strip attachments only if message size exceeds [x] bytes/KB/MB/GB
Select this option if you want to strip attachments according to the overall message size. Enter the maximum allowed message size in bytes, KB, MB, or GB. Only those messages that reach or exceed this size limit will have all of their attachments stripped.
Automatically expire attachments after [x] days
This option allows you to set the number of days for which attachments can be viewed after they have been stripped from a message. Once the expiration date is reached, the attachments are deleted. If the number of days is not specified, attachments will be kept forever.
Place links to stripped attachments in the body of the message
If you select this option, links pointing to the stripped attachments in your storage location will appear in a table (in either HTML or plain text format, depending on the format of the message body) within the body of the email message they were stripped from. The following information will appear in the table:
- Name of file(s)
- Expiry date of the item(s)
- Size of item(s)
The following screenshots show how a message looks like in a user's mailbox before attachment stripping has been implemented.
The screenshots below show the same message after attachments have been stripped (with HTTP links placed in the body of the message). Stripped attachments can also be accessed through a small Attachments.htm file attached to the message.
Choose language for replacement text
When you strip attachments from a message, it is possible to set the language of the headings in the table in which links to stripped attachments are displayed. You can choose from German, English, Spanish, French (France), and French (Canada). Note that this language setting is independent of browser settings.
Implementing Action Confirmation
The Action Confirmation feature allows administrators to give users Moderator privileges. A Moderator can review email messages caught by the Attachment Management policy filter before the messages are sent, which allows the Moderator to essentially override the default actions of the policy. After having reviewed the message, the Moderator can decide to send the message as is, encrypt the message, return the message to sender, etc. The Action Confirmation feature is configured in the Confirmation section. For more information on configuring this feature, refer to Action Confirmation.
Sample Attachment Management Policy
The following Attachment Management policy can be created to strip attachments from incoming messages (at the gateway) that are larger than 1 MB in overall size, delete stripped attachments from Netmail Store after 2 years, and place links in the message body for accessing stripped attachments:
1. Choose Policies > Attachment Management > Create Attachment Management Policy.
2. Enter a name for your policy, and then click Create.
3. Select your new policy from the list of policies that appear on the left-hand side of the Netmail Administration Console.
4. Select Strip attachments only if message size exceeds 1 MB.
5. Select Automatically expire attachments after 730 Days.
6. Select Place links to stripped attachments in the body of the message.
7. Click Save Changes to save your policy.
8. Select Domains. Highlight the name of your domain. The Policies tab is displayed by default.
9. Under Policies in Effect, click Assign Policy.
10. In the window that appears, select Attachment as the policy Type, select either Incoming for the Direction, and select the name of the Policy you have just created.
11. To apply the policy to all users in the organization, do not select Allow this policy to be overridden.
12. Click Assign to assign your Attachment Management policy.
Implementing Attachment Management Policies with the Attachment Management Agent
The Netmail Attachment Management Agent allows system administrators to use the attachment management capabilities of Netmail Secure to control incoming attachments into the mail system. To enable the Attachment Management Agent, choose Secure > Clusters > <Cluster Name> > Agents > Attachment Management. The agent should be Enabled in order to implement attachment management policies.