One of the ESPs I work in (maybe all) show stats for opens, and they include text versions. I know that you can create text version specific links that would give you stats on clicks, but how do we know if someone just opened the plain text email, but didn't click on anything?

Specifically if the email is sent as a MIME document, is there something sent back from the email client to the ESP that defines which version of the MIME doc is being viewed? I didn't think so, and if no tracking pixel is requsted, you wouldn't know if an email was opened... right?

I am thinking that my ESP is really just grouping all the click tracks together and reporting those as "opens", but maybe there's something going on I do not know about, which is usually the case in my life.