Alexei is a marketing representative for GL Food Bars and maintains a mailing list for 5,000 customers. His ISP alerts him that his email server is sending spam to millions of users at 100 messages per minute. What is MOST LIKELY the problem?

Domain 4: Communication and Network Security Practice Questions
Questions from the following topics are included in this domain:   
Assess secure network design principles.   
Implement secure network design principles.  
Secure network components using network access control devices.   
Implement secure design communication channels.  
Understand data communications and virtualized networks.