Signatures support using a square image in the signature.
Recommended Image size: 400x400
Changes happen only for future emails, not those that have already been sent.
To change your image you will need to edit your brand.
Account Settings and once the Account Settings open, select the Email Brands
Click the pencil icon next to the brand you want to change.
Hover over your image in your brand, and click the orange trash can.
Once deleted you can replace the image.
