Most times an "Intrusion Preventions Active" message is caused by the sending computer having a virus or malware. This is because the malware of virus is using the senders account to spew out mass emails. Our system will automatically shut that down. It will also automatically release that address after 1/2 hour has passed. In some cases, if it is an ongoing problem, your address will be relisted if the activity continues.
The best course of action is to scan your computer for viruses and malware, or bring it in to us to completely remove any viruses and malware.