An ERA finding released today said one employee complained to management and club manager Peter Lee suspended Ms Linnell after she admitted sending the email.
At a meeting on December 2 Ms Linnell apologised for sending the email and explained that she was not completely aware of the company's internet policy because she had not read it in full, the finding said.
But after consulting head office, Mr Lee was satisfied there was a consensus it was "one of the worst cases of offensive material they had seen" and Ms Linnell's contract was terminated.
Mr Lee said the distribution of the material brought the company's reputation into disrepute because the company logo was on the email.
He did not believe Ms Linnell had acknowledged the serious nature of her actions and how she had jeopardised the business.
Ms Linnell argued she had been singled out in a culture where computer policy was continually breached.
She also cited a discrepancy between two company computer policies. She said one policy said serious offending would result in dismissal and the other said it would see the offender lose their internet privileges.
ERA member Michael Loftus found the dismissal was unjustified because the decision to dismiss Ms Linnell appeared to be determined before the December 2 meeting.
He ordered that Les Mills pay Ms Linnell $915.90 in lost wages and $6000 in compensation for "humiliation, loss of dignity and injury to feelings".
Mr Lee said he was "disappointed" with the outcome and the company was considering whether to appeal.
"I don't think the ERA saw our point of view, they misconstrued a lot of the findings from the cross-examination. A lot of his findings were not what I believe was said."
Danny Gelb from Employment Dispute Law in Auckland said employees could be complacent about company policies, especially those who have worked in the same place for a long period of time.
Although he hadn't seen many cases of employers making an example of particular workers, the requirement that processes be "fair and reasonable" could complicate things.
One company he dealt with took an employee to the ERA for "pushing the boat out too far" in a workplace where workers often bent the rules.
To be fair and reasonable, the company had to then instigate processes against other employees for lesser offences.
He said employers often turn to the ERA to "take the moral high ground", despite out-of-court settlements being much quicker and cheaper.