. However, opening an unknown JS file on Windows can be dangerous because this is a way to prepare running executables. Google decided to increase security in the interest of users. However it is yet unclear if any warnings will be shown when receiving emails with JS files attached, sent from another email service provider. A bounce message is expected. If people still need to send .js files for legitimate reasons, they can use Google Drive, Google Cloud Storage, or other storage solutions to share or send the files. Generally speaking about security concerns at Gmail, Google isn’t saying that its staff are free to read the emails, but that all the emails will pass through its systems, and be scanned by its computers as part of the normal process of delivering them. It’s also one of the ways they identify the spam emails and put them in a junk folder.