Notification Email in HTML Format

OPTION-1
========
Using sqlplus as the apps user:

1) Execute the below update statements:

update wf_local_roles
set notification_preference = 'MAILHTML'
where user_flag='Y'

2)
update fnd_user_preferences
set preference_value = 'MAILHTML'
where module_name = 'WF'
and preference_name = 'MAILTYPE'

3) Commit

OPTION-2
========

1) Login to application with "Workflow Administrator Web Applications" responsibility.

2) Navigate as per below:
---> Administrator Workflow
------------>Administration
---------------> Workflow Configuration

3) Scroll to section "Global Preferences"

4) Change "Notification Style" to your desired value to have the preferences set as default values for all new users