"Police have been working closely with school staff and initial inquiries suggest there is no cause for concern."
The school is now open as per normal, Richmond said.
On the school website, principal Cherylene Neels last week said the emails were originally thought to be involved in hacking.
However, the emails "escalated in their tone" and the school sought help.
"In order to allow [the police] investigation to take place and provide a quick resolution, we have made the decision to close the school for the day tomorrow [Thursday, October 22]," Neels said in a letter to parents.
"I also realise that I haven't provided you the information you will be looking for at this stage, but I will be as open and transparent as I can once I have more information to share."
In the latest update which was posted on Monday, Neels said it was safe for students to attend school on Tuesday and listed several bullet points about the situation.
• "It is completely safe for your children to return to school tomorrow. The sooner we return to a sense of normalcy the better for everyone;
• "Please remain patient and calm. Wild speculation. and rumours do not help anyone, especially your children;
• "The Police are continuing to carry out their investigations. This has high priority with 3 Detectives working on the case, and they are following up a number of leads;
• "As soon as the Police have information that can be shared this will be relayed to the community;
• "Please do not bombard the teachers or the office staff with questions when you return to school. They are not at liberty to answer questions, and know just as much as you do."
A grandfather of a child at the school told the Herald in a text message the student's parents didn't know anything except hearing something about "threatening emails".
Richmond says detectives were taking the matter "very seriously" and they encouraged anyone with information to contact Orewa Police on 105.
Information about the threats can also be provided anonymously via Crimestoppers.