Immigration New Zealand is the latest government agency to breach the privacy of clients, says Labour.
The party's immigration spokeswoman, Darien Fenton, said immigration officials last week sent two emails with client email addresses to more than 200 advisers, lawyers and individuals.
It follows a Government shutdown of the Earthquake Commission's email systems after privacy breaches there.
Ms Fenton said the Government needed to move urgently to introduce a cross-agency solution to ensure every New Zealander's private information was safe.
"This incident comes on top of the public scandals of privacy breaches by state agencies including EQC, Work and Income, Inland Revenue and ACC," Ms Fenton said.
"If the Government can't even get the basics right, like protecting the personal email addresses of Immigration NZ clients and stakeholders, how can the public have confidence that their privacy is being protected?"
Immigration spokeswoman Rachel Purdom said the emails included the email addresses of licensed immigration advisers, lawyers and others who had registered to receive updates on matters relevant to giving immigrationadvice.
She said the addresses were mistakenly shown in the "cc" line rather than "bcc".
"No personal details were released apart from the email addresses," Ms Purdom said.
Staff will be issued a reminder about the protocol for sending group emails and an apology will be issued to those affected.