Vodafone was within its rights to sack an employee for sending inappropriate emails from a work address to staff and friends, including comments that she was not really sick but was going home to go to the toilet.

The Employment Relations Authority ruled Vodafone NZ was within its rights to fire Papataia Toleafoa from her call centre customer service representative role in February, and declined her personal grievance application.

The company began monitoring Ms Toleafoa when she sent out an email to 200 employees on January 18 asking if anyone wanted to join the union and referred to upcoming salary reviews.

She was warned to not use her work email for personal use, and told management she would not do it again.

After the warning, Ms Toleafoa sent emails to friends from her work address that included derogatory remarks and said she was going home early for false reasons over the course of January 20 -25.

"I'm off home, coz I've told my pule that I'm going home coz I'm stressed. Aoooo, fia ki'o more like it," she wrote in one email.

The authority translated the word "pule" to mean boss and phrase "fia ki'o" as meaning "going for a s***".

Ms Toleafoa took sick leave on six days between January 24 and 31 claiming she was stressed, the report said.

Emails over this period also called fellow staff dickheads and f***wits in Samoan, and said a staff member "talks like a cow chewing on grass".

Ms Toleafoa was also seen to ignore a business call and talk on her cellphone on January 21, which she agreed she shouldn't have done.

Authority member Robin Arthur ruled the language used in the offending emails justified a finding of misconduct.

A Vodafone spokesman yesterday said the company was pleased the authority supported it.

He said the company hadn't had to issue a collective warning to all staff about the correct use of work email, but the decision did "reinforce our clear messages about what acceptable behaviour looks like".

He said although Vodafone did not actively monitor employee email use, it reserved the right to do so if there were indicators of inappropriate usage.