Excluding attachments by fingerprint

1 Introduction
2 Creating a new fingerprint exclusion rule
- 2.1 Create field options

Introduction

As an administrator you may desire to exclude a specific attachment file. A file can be uploaded to JEMHC which will generate a fingerprint (An MD5 hash) of the file, subsequent processed attachments that match this fingerprint will be excluded. Fingerprints are generated from the exact content of the file, if any part of the file is modified then the fingerprint will change. An image file for example may look identical to another file, but this is no guarantee that the fingerprints generated from both files will match.

Fingerprint exclusion configuration can be accessed by pressing the Exclusions button within the JEMHC navigation bar and then pressing Exclude attachment by fingerprint.

Creating a new fingerprint exclusion rule

JEMHCloud maintains an internal list of common images found in emails that aren’t desirable for attachment. They are loaded from Jira Cloud every 24 hours, which should provide a good match for common images that are included in Jira Cloud (support for External Gravatar based images has not yet been added). You can view the automatically excluded images by toggling the Show Jira Images option within the automatic exclusion notice.

Pressing the Create button will trigger a popup window where you can upload files to be fingerprinted for exclusion. Using the Files field you can select an individual file or multiple files to upload to be excluded. In this example an image of a cat is to be excluded. You can scope the exclusion rule to a project via the Project drop-down field, global scoped rules will apply to all projects.

Pressing Upload will upload the selected files and create the rule. The hash fingerprint of the file is shown alongside a preview of the file (if it is an image). The Last Seen and Times columns will show you how many times the excluded file has been seen in your instance and when it was last seen.

Create field options

Project

This defines the projects that this exclusion should be applied to. Global means that it will be applied to all Projects.

Files

This is where you select individual files that you would like to exclude. You can select up to 20 files at once.

Zip Files

This allows you to upload a Zip file that contains all of the attachments that you would like to exclude. This Zip file must be less than 10MB