All review participants will recieve an email for each comment made (and depending on the profile setting, the comments are batched or individually sent). If you are not a review participant, you will not get an email.
Right now, there isn't a way to add 'watchers' to reviews - that is, they aren't a review participant, but still recieve notifications.
You might workaround that by subscribing to the RSS feed of reviews for the project, but that will give you all comments for all reviews in that project. Alternatively, there is an email review function in the tools menu that allows a user with view review permission to send that review as an email to anyone (either a user or an arbituary email address).
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