Can you setup a HTML email signature in iCloud?
If you are logging into your iCloud account online at www.icloud.com, you cannot add a HTML email signature. This is because the www.icloud.com Mail app does not support HTML email signatures.
How to add a HTML signature to your iCloud emails
Therefore, the only way to add a HTML email signature to your iCloud emails is to import your email into a supported email client, like Apple Mail, and follow our instruction guides for installing your HTML email signature in these programs instead.