Sender Score is a reputation monitor from Return Path. Using algorithms, your Sender Score gives you an idea of what your IPs reputation is as compared to other senders.
Before sending out your company emails, send them through the Spam Check to see what popular spam Filters view as spam infractions.
DomainKeys validate that the domain of the from address matches the domain that is sending the message. DomainKeys do not validate the domain of the return path.