Google just announced a new experimental feature for Gmail: background send. Thanks to this new feature, which you can activate in the Labs section of the Gmail settings menu, Gmail can now send emails in the background. This will save Gmail users a few seconds every time they send an email.
Once you activate this feature, Google will start sending emails in the background and allow you to continue browsing your inbox while it’s doing so. No need to wait for it to finish sending your messages anymore.
Just in case something goes wrong, a new message will pop up at the top of the screen that gives you the option to fix the problem now or to wait until later. These error messages will, according to Google, “stay around until you decide to fix things, so you don’t have to stop whatever you’re doing right away.”
Just Don’t Close that Browser Window…
Google does warn, though, that you better keep Gmail open until all your background messages have been sent. If you don’t, Google warns, “your messages are probably going to be lost.”