Microsoft sued in June last year after noticing that a large number of third party e-mails, which promised automatic Windows updates after users downloaded a toolbar, were passing through its servers.
In January, Microsoft was awarded a summary judgment that found Khoshnood and Pointcom guilty of breaching anti-spam laws, and prohibited them from spamming or from using Microsoft's trade marks.
Last week Judge Manuel Real of the Central District Court of California upheld the ruling and awarded damages of $3.95 million.
The case is just one of 60 that the Redmond based company has filed against spammers since it launched its anti-spam campaign last year.