Macworld A standard block or text—or signature or .sig—at the bottom of an outgoing email message dates back decades. Modern email software, like Apple’s Mail app for macOS, gives you full access to design a signature, including rich formatting, links, and images. Those options are mostly lacking on an iPhone or iPad. How can you bring some verve to your “.sig”? You have several options. Use limited formatting in SettingsIf you go to Settings > Mail > Signature, you can select the text (tap and then tap Select All), tap it to bring up a popover menu, tap Format, and then choose Bold, Italic, o…