title: Store email password in a shared server database
body: <p>I'm building an application using php for server side code, at the moment the customer has a shared server with linux and a mysql database (yes I know it is an horrible solution, but they don't want to spend more money).</p>
  
  <p>The problem is: they asked me to store their email addresses with relative passwords in the application, so they can contact their customers from different addresses without inserting password everytime, but my problem is: how?
  I mean, if I use one-way encryption it'll be more secure, but I have to ask password everytime to verify, two-way encryption is more comfortable, but not safe.</p>