Hi, I wrote it. It does ask for a lot of permissions when you install it. I expect that to make privacy folks wary. But, the plugin has to make queries against your gmail to get the last email date, and it needs to, of course, query your contacts.
Now, one other permission that it asks for is to contact an outside website. I make an HTTPS request to my domain, sending your gmail address and the add-on version. Right now, I just use that info to render the sidebar footer. In the future, when I update the plugin, potentially to a version you have to pay for, I would use your email as a filter to show you a sales dialog on load, and also to change your footer.
The first version of the add-on will always be free. But since Google Add-ons make you roll your own payment story, I added in the simple phone home call to test premium features.
