Thanks for the suggestions.  When I created an alias of "Memo" for form "testForm", the doc is still received in the mail-in db with all the fields that are contained in a standard memo form (e.g. body, categories, delivereddate, MIME_version, PostedDate, etc).  The field that is supposed to be created from the button code, response1, is no where to be found.

Something in the routing of the email to a mail-in db is different (at least in my case) versus the routing of an email to a mail db.  When I use the button code to send to a mail db, the doc is received with form="testForm" and field "response1" is present and contains the sent value.  Granted, a few additional fields get added during the routing process but the fields specified in the button code all come through intact.

I did try the "Store form in document" setting to no effect.  The doc hits the mail-in db already morphed into a memo with all the memo field and none of the fields created from the button code.