If your email is bouncing, it is possible that the reason is because another person on the same IP address was spamming.  In this case, the spammer could have gotten the shared IP address listed on a spam "black list" somewhere on the Internet.

You can check to see if your server is on a spam black list here.   http://mxtoolbox.com/blacklists.aspx

If you do find that your server is listed on a black-list, open a support ticket with our staff (click "contact" at the top of our web page) and include as many details as possible so that we may troubleshoot this.

If you want your own dedicated IP address, contact our sales team and we will be happy to quote you a price for your own dedicated IP address, so you will not need to worry in the future about spammers.  In other words, if you have your own dedicated IP, your email will not be affected by others.