The e-mail address that a given backer uses for their Pledge Manager account cannot be changed by us if the backer has pledged to projects other than a project run by Dwarven Forge.
To change their e-mail address, the backer must log into Pledge Manager and use the top right navigation to go to "Preferences."
In Preferences, the backer may change their e-mail address.
If you cannot change your email by this method, please contact Pledge Manager at support@pledgemanager.com.