By design, your data stays at all times on your Google Spreadsheet. Here's all the data we need in order to make Mailmeteor work:
Your email address - to know who you are
If you are a paying customer, your name to identify payment
Campaigns sent metadata (date of sending, sheet's name - that's all)
Emails sent metadata (email ID in Gmail, date of sending, opens and clicks events - that's all again)
Mailmeteor is a verified G Suite add-on. Read more about Google verification process.
Mailmeteor only requests permissions to send emails and does not require access to your email data, contrary to other mail merge add-ons. This means Mailmeteor cannot read, modify or delete your emails by design. When installing Mailmeteor, you can review all permissions required.
Why does Mailmeteor require this permission?
See, edit, create and delete your spreadsheets in Google Drive
Mailmeteor essential functions are done from within your Google Sheets (such as filtering emails, adding a tracking report, sending personalized emails).
Send email on your behalf
Mailmeteor core functions is to send emails automatically from Gmail. This permission allows Mailmeteor to send emails with Gmail. It is used only in this context.
Connect to an external service
Allows Mailmeteor to send and retrieve information from Firebase, a real-time database from Google. Your data stays inside Google environment.
Display and run third-party web content in prompts and sidebars inside Google applications
This scope is required to display sidebars inside Google applications. Mailmeteor uses this permission to display the tracking report.
Every time you send a campagin with the email tracking enabled, we generate random and unique Mailmeteor IDs for each recipients in order to track opened emails and clicks. These IDs are added as notes to each cells in the "Merge status" column.
Emails data is anonymized, Mailmeteor never store the email addresses of recipients who opened or clicked emails.
You can turn off email tracking before sending a campaign by opting out the box "Track emails opened and clicked"