In some cases your Internet Service Provider blocks certain ports so that viruses and other malicious programs cannot send email from your computer. This is a preventive measure and does not mean at all that your computer is infected.
To resolve this issue, try changing yout SMTP port for OUTGOING MESSAGES to: 25, 26 or 2525.
If this solves the problem it means that the port was blocked.
If the issue is not resolved please feel free to contact our tech support team.