The email said: "Please be advised that we require you to delete the following album from your Beatbox hard drives and any other storage media as the music is no longer available for licensing effective immediately."
When contacted today, Beatbox Australia said the company did not wish to make any comment.
A video music producer, who did not wish to be named, said he used Beatbox's music library of over 300,000 tracks.
He said an album titled Sound Alike contained roughly 60 tracks -- one of which was called Eminem-esque. He confirmed this was the track that was used by the party in its campaign advertisement.
Other track titles on the album included Beyonce-esque, Rolling Stones-esque and Bruce in the House, a reference to Bruce Springsteen, he said.
"It was a trend they started doing a few years ago with these sound-alikes -- they are all going to be in the style of the artists which is perfectly legal," he said.
"But the problem might come if it infringes on intellectual property rights."
He said the the music library offered clients certain ways to search through music -- for instance, by styles and tempos, or key words.
"They weren't necessarily searching for Eminem, but the fact that this song is called Eminem-esque ... it says they would have known it would be in the style of Eminem."
Copyright lawyer Chris Hocquard said he did not believe the title of the track would strengthen a legal case against the National Party.
"Ultimately whatever the song is called is irrelevant," he said.
Typically in these cases, the copyright holder would argue that copyright was infringed, and the party was trying to "pass off" a track as the original.
"They bought a track that has a name that's called Eminem-esque, it sounds quite like an Eminem song ... They just thought it was okay that's all it is.
"They're not pretending that they didn't even think it sounded like Eminem, they are just saying that they thought it was perfectly okay to use it because it was available."
Meanwhile, a MediaWorks spokeswoman confirmed it had pulled the advertisement with the track from the air two weeks ago.
She said new advertisements had been playing since and although they had a "similar vibe" they were different.
