Cumulo9 has published new data showing open rates for essential business emails in New Zealand fell to 63.6% in 2025, while click-to-open rates rose to 6.7%.
The findings come from the sixth edition of its Essential Email Insights Report, drawing on data from millions of emails, including invoices, payslips, statements and notifications sent by large businesses, non-government organisations and public sector bodies in New Zealand.
Open rates declined for a second straight year, down from 68.5%. At the same time, the rise in click-to-open rates from 6.2% suggests recipients who do open messages are more likely to engage with the content.
Industry split
Performance differed sharply across 18 sectors. Local Government recorded the highest open rate at 68%, followed by Financial Services and Travel & Tourism at 67%, while Media & Entertainment and Utilities both reached 66%.
Insurance stood at 63%, close to the overall average. At the lower end, Real Estate posted 48%, Investments 49%, Charities 52% and Banking 54%.
The data also points to a link between message frequency and readership. Organisations sending monthly statements achieved higher open rates than those contacting recipients only twice a year, indicating that regular communication can lift engagement even in sectors where customers may not act on every email.
Only two sectors recorded year-on-year gains in readership: Financial Services, up 1%, and Insurance, up 2%.
Database quality and technical standards also varied. The Health sector recorded 99.99% address accuracy, while the Charity sector reached full compliance with SPF, DKIM and DMARC email authentication after lower adoption a year earlier.
David Allen, General Manager of Cumulo9, said the report is intended to provide a local benchmark for organisations handling essential communications.
"The Essential Email Insights Report reflects the real-world email behaviour of a vast New Zealand user base and gives marketers and operations teams local benchmarks to improve their essential email performance," said David Allen, General Manager of Cumulo9.
"Email receipts and open rates are measurable, an important advantage for sectors like utilities and financial services where service providers must be able to prove customers opened important communications," Allen said.
Changing patterns
The report suggests established assumptions about the best time to send emails are shifting. Fridays overtook Tuesdays as the strongest day for opens, while Mondays generated the highest click activity.
That gap points to a difference between when an email is noticed and when a recipient acts on it. Monday evenings between 8pm and midnight delivered the highest open-rate window at 70.05%.
More organisations also moved away from standard office-hour delivery. Emails sent between 4pm and 8pm on weekdays rose from 10% to 13% of total volume as senders tested later delivery.
Cumulo9 said timing messages at unusual moments, such as seven minutes past the hour, can reduce competition from bulk email traffic that often arrives exactly on the hour.
Mobile devices remained the main point of access, accounting for 66% of opens, although growth in mobile share has levelled off. Recipients often first open essential emails on a phone and later return to them on a desktop, reinforcing the need for messages to work across both formats.
Tighter controls
The data was gathered during a period when major mailbox providers introduced stricter requirements for senders. Microsoft now requires bulk senders to Outlook.com, Hotmail and Live addresses to use SPF, DKIM and DMARC authentication, provide one-click unsubscribe and keep spam complaint rates below 0.3%.
Apple has also tightened its DKIM rules by requiring RSA SHA-256 signing as a minimum standard. Those steps mirror moves already taken by Gmail and Yahoo and add pressure on organisations to meet baseline technical requirements if they want messages to reach inboxes rather than junk folders.
Allen said the changes reflect a wider shift in how mailbox providers assess email legitimacy.
"Mailbox providers are raising the bar continuously. Microsoft's bulk sender requirements, which came into force in May 2025, and Apple's tighter DKIM standards reflect a broader industry shift toward treating authentication as a baseline expectation," Allen said.
"Our data shows the organisations with the strongest open rates are operating cleaner infrastructure. The Health sector's 99.99% address accuracy is a good example. That kind of database discipline reduces bounce rates, which protects sender reputation and in turn improves deliverability and open rates in a virtuous circle," Allen said.
He added that the basic requirements for email delivery remain unchanged even as reader behaviour evolves.
"The fundamentals remain true: get your SPF, DKIM and DMARC sorted, keep your database clean, and design mobile-first," Allen said. "But user behaviour has changed. The old rules around send days and times no longer hold. Test, measure and adapt. Email is still one of the most cost-effective and measurable channels available, so make the most of it."