Thanks to a built-in translator, Mailspring makes communication in other languages much easier, but this free email app for Mac also has a spellcheck feature to check your English spelling mistakes. Mailspring comes with a built-in email signature editor, allowing you to create a dazzling email signature, with your picture and links to your social media, in a matter of minutes and without spending any money at all. Most professionals these days are well aware that email signatures leave a lasting impression, and they sometimes pay several dollars each month for them.