In the middle column, type a name for the signature.
The name appears in the Signature pop-up menu when you write a message.
In the right column (the preview), create your signature.
You can use the Edit or Format menus in Mail to change the font or layout, turn text into links or check spelling. To add an image, drag it into the preview area.
If you want your signature to appear after the original text of messages you reply to or forward, unselect the “Place signature above quoted text” tick box.
In the Mail app on your Mac, click the Signature pop-up menu in the message you’re writing.
Choose a signature.
If you don’t see an expected signature in the pop-up menu, choose Edit Signatures to open Signatures preferences and verify the signature is in the account.
In the Mail app Send and receive vCards in Mail on Mac