Yes, both our Linux and Windows VPS packages can be used for email marketing as long you abide by U.S CAN-SPAM laws.  Furthermore, clients are not allowed to send out emails to users who didn't opt-in to receive your emails. 

If we receive any spam complaints, we will be forced to suspend the vps account. We have ZERO tolerance for spam on our network.  There is a $500 fine if our IP is blacklisted for spamming. 

For more information on CAN-SPAM, please visit - http://business.ftc.gov/documents/bus61-can-spam-act-compliance-guide-business