I know this seems kind of backwards, but I was asked to put a link in an email to the plain text version for viewers whose emails are not displaying the emails correctly. I looked through the glossary and the help pages but didn't find any tags.
How do email services decide what version of the email will be displayed, html or plain text?
It's up to the individual email client as to how it decides - typically though, if a client *can* show HTML, it will, unless there is a specific preference set.
Really though, the webversion might be the best option for people who are seeing a messed up HTML email. You can't really link to the text version.