Unconverted guests will not be emailed when a message is sent out to the class.
Only converted guests (those with studio accounts) will receive the message.
When registering a guest, an optional email address can be included for the guest. If there is no studio account associated with the email, the guest will be an "Unconverted Guest".
If an admin messages the class, the unconverted guest will not be included, despite having entered an email for them when booking them into class.