For your first question, you'll need to set this up in your email client, depending on what you use. For example this is Outlook: Read email messages in plain text - Outlook
For your second, My Tokens don't use default values in the same way that Lead tokens do. Since My Tokens are defined at the program/folder level, they'll always be present when the Email is rendered. Are you trying to use this as a replacement token for Request Campaign or something?
Thanks for your response. I adjust the Outlook settings, and I could see the text-only version, so thanks.
For the second question, a solution was figured out so that we can see text version of html and the tokens are displaying correctly.
I want to thank you for your response and help!