1. To attach a filt to an already existing mail template, go to 'Administration>Guest Messages' and click pen-icon at the selected template.
2. Click attachment icon, it will open a side panel on the left side of the screen.
3. Click select or drop the files you want to attach in the grey box. Click Apply to upload them. And Click 'Save' in the Guest Message view.
4. If you have attached files in the template there will be a number displayed on the attachment icon, you can click the icon to view attached files.