What about the time you clicked on that PayPal link that wasn't really a PayPal link? "Phishing" is a term applied to either websites or emails that pretend to be something they're not in hopes of getting a user to click on something they should have ignored. This tactis is done in hopes of then getting users to provide confidential information they would have otherwise kept to themselves, typically like passwords, financial information, or other personal data. While there are security measure that fight this, the mechanics behind phishing are, unfortunately, also consistently becoming more sophisticated. Even some dedicated antivirus and business-class hosted endpoint protection suites are having trouble keeping up.
Our aim is to keep our servers clean from malware, phishing, and other malicious activities posing threat to Internet users. It does not mean that we judge before knowing you, but today's reality is that we can not predict intentions of every user who signs up. In order to prevent misuse of our services we had to apply certain limitations to free hosting accounts. In turn our servers are never blacklisted so you can always expect your email message to reach it's recipient, and Internet users to reach your website.