Hi,
It looks like in Smartlist Builder, you were able to add the SY01200 (Internet Addresses) Table to pull in information for email addresses. The fields that will hold the email addresses in this table are the Email To Address, Email CC Address and Email BCC address. You can limit the returns into the Smartlist by setting the Master Type = 'CUS' and this should show all the customers you have setup with email addresses.
If you are using GP2010, you will want to fill out the email address that would be found under Options on the customer card. In here, you will see an area near bottom where you populate who you want to receive the statement. This email information is held in the RM00106 (RM Statements Email Addresses) and will only have a record if you have actually entered email address within the field. So if you are attempting to populate records, you will need to actually insert records into this table to correspond to correct customer id associated.
In GP2013, we have introduced capabilities to email statements using the Word Template functionality that allows customers to use the template functionality.
Thanks,
Jamie