You can include a signature block on the inside of your Enthusem cards. It will go all the way at the inside bottom of the card. Attached is a Photoshop template that shows an example of how you could use the signature image feature for your Enthusem cards. There are no specs other than the size which is 4.5" x 1" 300 dpi. The signature is centered in the bottom of the card and has a white margin on either side so your signature image will not bleed to the edge, therefore you can have text right along the edge of the image without worry that it will be cut off.
Once your image is complete, save as a jpg and go to your Enthusem account. Click on the down arrow by the photo icon at the top right corner. From there click on Settings>Signature Image and upload your jpg.
IMPORTANT: It is always recommended that you preview your Enthusem cards prior to sending to ensure that the image is lined up as you intended. You are responsible for using this template correctly should you decide to do so.
NOTE: As long as you have images uploaded on the "Manage Templates" page, they will ALWAYS be used (for that user account) unless they are removed by the user. If you need to change signature images for each mailer, you need to do so prior to placing the order for your mailer.