Attachment Block on Size polices allow administrators to block delivery of attachments over a specific file size. The recipient receives only the email body with a message informing them of the attachment's removal. This policy applies to individual attachments over the specified limit, as well as any email where the total combined size of all attachments exceeds the specified limit. Individual file sizes will be considered before cumulative sizes. For cumulative stripping, there is a minimum file size of 50k before an attachment is stripped.
For example if the policy is set to 10MB, an email with 5 attachments with a cumulative size of over 10MB, the policy is triggered and all the attachments will be removed.
With compressed files (e.g. .zip, .rar, .7z) the policy considers the unpacked size of a compressed file rather than the compressed size.For example if a .zip file is 4.5MB compressed, but the contents total over 10mb when unpacked, the file will trigger a policy set to block attachments over 10MB.
It is possible for multiple policies / actions to be applied, as individual file size restrictions will be considered first followed by the cumulative limits. For example if a Strip and Link attachment policy is configured to trigger on attachments over 10MB, and an Attachment Block on Size policy is configured to block on attachments over 15MB, the following behaviour can occur (1 attachment being 11MB and 1 attachment being 5MB in size).
- The 11MB attachment will have the Strip and Link policy applied as it exceeds the configured limit for this policy based upon on the individual file size. The 5MB attachment is too small for the Strip and Link policy to apply.
- The Block on Size policy will be applied due to the cumulative size of all of the attachments.
The above behaviour will be outlined in the resulting notification that is generated when the above policies are applied. This is dependant on your configured notification settings. For example:
Action Taken : Stripped and Linked
Reason : Contributes to exceed size policy of 10485760
Action Taken : Stripped (Blocked)
Reason : Exceeds size policy of 15728640
What You'll Need
- An Administrator Console logon with access to the Administration | Gateway | Policies menu item.
Administrators can release these attachments via the Administration | Monitoring | Attachments menu item in the Administration Console. As the attachment has been placed on Admin hold rather than User hold.
Creating a Policy
To create a policy, follow the instructions in the Creating / Changing a Policy article, but using the following options:
|Policy Narrative||Provide a description for the policy to allow you to easily identify it in the future.|
|Maximum Attachment Size (KB)|
Specify a value in Kilobytes for the maximum file size of all attachments in a message. Any attachments that exceed this limit are removed from the message. For example if 1000 KB is specified and a message has two attachments of 550 KB each, both attachments are removed.