How do I add my email signature to Spark Mail on iOS?
Spark is available as a free download on the App Store.
Open your signature on htmlsig.com and click Open in New Tab.
Select and copy your signature to your clipboard.
Open Spark and tap the menu icon in the top-left corner, then tap Settings.
Tap Signatures and make sure Use Email Signatures is turned on.
Tap Add Signature.
Tap into the signature field and paste your copied signature. If you're pasting raw HTML code instead of the rendered signature, tap HTML in the top-right corner first, then paste.
Tap Set as Default for... and choose the email account this signature should apply to.
Tap Save.