Majority of smart-phones nowadays come with special Mail apps (applications). These are designed to serve two purposes.
In the first instance, they collate mails from various mail systems, so that the smart-phone users can access them centrally. Thus if, for instance, one has mail accounts at www.hotmail.com, www.yahoomail.com and www.gmail.com a smart-phone mail app with the right permissions is capable of putting them all together, so that the smart-phone user can access them from one place. Most of these smart-phone mail apps are also capable of giving out sound alerts whenever new mails are received. This ensures that the smart-phone users get to respond to their mails expeditiously.