One of my fields is missing from the email notification

On my resellers form, I have Seller's Forwarding Address as required but it doesn't show up in my email.

While editing your form, click on the "Emails" tab.  From there, select your email notification and click on "Edit". 

Add a new row to the table in the body of the email and insert the forwarding address field ID.  This will add the forwarding address to your notification email.

You can also create a new email notification.  That will give you a notification with all current form fields.