Nintex Workflow Sending Duplicate Emails

ISSUE

When trying to send emails to the members of a large SharePoint group, the workflow instance sends duplicate emails.

Option 1

Assign the email action to an Active Directory Mail-Enabled Security Group, to have the email action processed by Exchange instead of SharePoint.

Option 2

Add a one minute pause at the start of the workflow design. This gives the workflow engine enough time to instantiate the group members initially, resulting in just one email being sent.