Interesting!
Spark is already one of the most expensive internet options. But many people have had the @xtra.co.nz emails for decades and if you leave Spark you lose access to your email (or, I guess, can keep it if you pay $6 a month).
Interesting they now want to discourage customers from being locked in to their service. Maybe they hope to compete on price by cutting this, or maybe the price per customer is too high as many people now use free options.