A Perth-based 'spam house' was raided on Thursday by the Australian Communications Authority as part of an investigation under Federal anti-spam legislation.
The company responsible for the premises in question has not been named.
"The ACA has received reports from members of the public alleging that they have received thousands of unsolicited e-mails sent by this company," said ACA Acting Chairman Dr Bob Horton.
"Further investigations suggested that this was only the tip of the iceberg."
The ACA "reasonably suspected" the company has sent tens of millions of unsolicited commercial e-mails (spam), and as such was in breach of the Spam Act 2003.
ACA inspectors seized computer hard disks and other material as part of the search. They were also aided by Deloitte Forensics and lawyers from the Australian Government Solicitor.
The company and its sole director must report back to the ACA within two weeks.