Q & A: If I add an email to a Box, can I delete the email from my Gmail account?
When you add an email to a Box in Streak, we're creating an association between the Streak Box and your existing Gmail. The thread itself stays happily at home in your Gmail. The next time you access the email from within your Box, we will send a request to your Gmail account to retrieve the email based on the email's thread ID. If you delete your emails, in 30 days Gmail will automatically delete your emails forever to cycle out your trash bin. When this happens, Streak will be unable to redirect you to the message in your account and you will loose access to this email forever.
Instead of deleting your emails after adding them to your Box, we suggest archiving them. This way, your emails will still be removed from your inbox and out of view, but will be kept in your account so Streak will always be able to redirect you to them from your Box.