I think you misunderstood what I was trying to do. I wanted to change the default selection on the form itself that so that when a customer is being added in manually, something that will happen on occasion, the person entering in the info doesn't have to remember to change HTML to TEXT for the email format.

I managed to figure it out for myself this morning. I made the following change to add_customers.php.

Code:
$email_pref_text = ($cInfo->customers_email_format == 'TEXT') ? true : false;
changed to

Code:
$email_pref_text = ($cInfo->customers_email_format == 'TEXT') ? true : true;
By the way, since the default setting in the database is to put TEXT into the email preference field, if there is nothing in the CSV file to override that, any customer entered via CSV is going to automatically be set to TEXT, so what you suggested wouldn't be necessary for my situation. Adding that column, however, would be useful for store owners who want to preserve customer email preference settings from an old store. In that situation, I don't think it would be necessary to make that change to add_customers_backend.php, though.

Thanks anyway for your attempt to help.