I want to make voting super easy for users and want to be able to send them an email with a summary list of ideas to be voted on with an Up/Down vote button beside them in the HTML email. Is possible to vote this way or must we go into the idea on Jive and vote from there?
There is not a way to cast a vote via email but there is an options for a POST API call to cast a vote.
Although the only two supported methods are to use up vote the button in the UI and the REST API's, you might consider asking in the Developer space to see if anyone else has customized alternatives.
Hope this helps.