When setting up your email it’s better to use SSL, especially on mobile devices. Here is a explanation of why SSL is safer.
When a mailbox is popped using standard POP3 protocol, the username and password are sent in the clear over the internet. This means, that anyone with the ability to “listen in” on your mail client’s login session with your mail server can easily retrieve your username and password as well as read your email. In addition, once they have your password, they could read your email without your knowledge or permission or they could even send SPAM email from your account, possibly getting you into serious trouble since spamming is a crime in most Western countries these days.
The best way to ensure no one can get your password (at least not without going to a huge amount of trouble) is to POP your email using a Secure Socket Layer (SSL) connection. This means that all data exchanged between your mail client and the server is encrypted with a digital security certificate making it [pretty close to] impossible for anyone with malicious intentions to steal your email and/or password.