By design, this setting is locked down and cannot be changed within the latest Nokia Messaging client. 

However, this setting can be changed on the following devices because they are running an email client that is built into the firmware:

  • Nokia E52
  • Nokia E55
  • Nokia E72
  • Nokia E75
  • Nokia E73
  • Nokia E5-00
  • Nokia N86 8MP
  • Nokia 6710 Navigator
  • Nokia 6730 classic
  • Nokia C5-00