Why do I see a mix of HTML and text versions in my test?
Some ESPs send out both a plain text version and an HTML version of your email separately when sending out a test/proof email. In this case, you may find that using the using your unique Litmus test address (available in the Settings tab in your account) produces better results for your test emails sent to Litmus.
Your unique Litmus test address is permanent and reusable. Using the unique Litmus test address will create two separate tests: one for the plain-text version and one for the HTML version of your email. You'll see these as two different tests inside your Litmus account.