Redmine

You can add a reference to an image to the footer using the same syntax you can use from inside your issues, e.g.,

• !https://www.redmine.org/attachments/7069/Redmine_logo.png! (if you are using Textile)
• or ![](https://www.redmine.org/attachments/7069/Redmine_logo.png) (if you are using Markdown).

However, you would need to make sure that the image you reference there is available on a public website so that mail clients are able to download it. Uploading the file as an attachment to a private Redmine will likely not suffice. In any case: the image file will not be transferred along with the email. Also, to prevent tracking, many mailclients don't automatically load external images by default.