Setting up a personalized email will make it easy to send one-off emails to individual voters (e.g. to follow up and remind them to vote), without having to write the email more than once.
How to make your one-off emails pre-populate
In your ballot's Settings, click the More Settings text
Write the email that you anticipate sending to voters individually. Use merge fields to automatically send the right information. Again, this is most often used to follow up with individuals who haven't yet voted, but you may find other use cases.
When you want to send this out to individual voters, follow these steps