Gmail to Evernote is a Google Apps Script, developed by HarryOnline.
We don't collect or store your data, period.
The script runs on Googles servers, so we don't have access to the information you supply anyway.
When you use the script, it will check every day if there is a new version. If there is any relevant information about a new version, it will send you an email message. The message is sent by the script (you will see yourself as the sender), we have no access to your email address.
The file with version information and possible relevant messages is stored on our server, so from the server statistics I can see how many users there are. No personal information is received or stored in this process, not even your IP address, as the information is requested from the Google servers.
For all details, read the source code of the script: from the menu in the spreadsheet, click Tools - Script Editor