I've got a list workflow that sends out an email to a user based on a workflow lookup for the current list item. I've set it up to send the email to the email address of the user named in the "Waiting On" field.
When I use myself in the "Waiting On" column, the email is generated and sent properly. However, if any other user is named in the field, the email is addressed to their UserID Number.
Instead of showing up addressed to firstname.lastname@example.org, it appears addressed to: 9