In short:
Yes you can get Port 25 Unblocking on UnPlan and Wireless Broadband (4G/5G)
ADSL/VDSL/Fibre:
- No static IP Needed ($15 Per Month)
- Apply Here: https://www.spark.co.nz/forms/port25-unblock/
Wireless Broadband
- You need a Static IP due to CG-NAT ($15 Per Month)
- Should be using Newer B618 router as B315 doesnt play as well "Very Clunky".
- Apply Here: https://www.spark.co.nz/forms/port25-unblock/