Ok, Here is my scenario.  Registration form 1 has two fields "userenteredtext" and combo box "@domaina.com", or "@domainb.com" etc..  SQL event contecates (I think verbage is correct) two fields and inserts into dnn core email.  here is the SQL:
Update Users
Set Email = '$(userenteredtext)' + '' + '$(domain) '
Where UserID = $(UserID)
Upon submit, user is redirected to Registration 2, where OptIn Email integration is enabled.  Reason it is redirected is depending on user selection email address is either entered manually or created by above and redirected to different locations.  Registration 2 has email linked to core and pulls the "created" data (EmailAddress) and inserts into OptIn list perfectly upon selecting and submitting.  THE CRUX:  A requirement in development is the email address in Registration 2 must be hidden.  As soon as I change it to a hidden field, the OptIn list is populated with first and last name, but email address is N/A.  Have tried numerous SQL Completion Events, all resulting in a blank "Email Address".  Can somebody help me please!!

Hi Chad,
Here is an update on situation:  Tried to change Email field to textbox but the field would not ever change, stuck on hidden field type.  Deleted question, added it again, linked to core, then changed field type to hidden.  It started working!  Today, back to not working .  Changed Email field type to textbox (it let me this time).  Textbox was empty when viewing form as host.  Linked to email in dnn core, updated and now email address populated in textbox with correct email address.  Created new user and OptedIN.  Success again!  No need to reply unless you know it going to fail again in the morning and have a solution...I will post tomorrow whether it "stuck" or not...
Steve

Oh, I did have two more questions.  What is the proper way to "unsubscribe" a user when using DR?  I have set up a lot of test users and need to delete them.  AND the 'test@theiremail.com" (no DNN User) that i did with the DynamicForms SQL stored procedure is not found in "Manage List/Users", although OptIn is still sending messages to this user (I get Exchange bounce backs after awhile)?

I'm having the exact problem with hidden email field type and the Opt-in integration. The checkbox for the Opt-in category is not populated nor are changes saved. When I change to a textbox, there's is no problem.

I think here's a bug, Chad? Maybe it has something to do with the fact that you can't integrate a hidden email field with the core ... at least the hidden email field is not shown on the core integration dropdown list for the email core integration???

Mine did finally "stick" using short name of "EmailAddress".  You might try deleting question, create a new question "Email Address", short name "EmailAddress", leave as text box and link to core dnn Email Address, verify it is populating by viewing the form.  If so, manage question, change to hidden field and update.  create a new test user with form, register, then check in user accounts to see if it populated..........I'm not sure why this worked for me, but it did.........Good Luck.

Thanks Stephen,

with your help I got it to work.

But still, I hope this will be fixed in future versions.