I’m sure you have faced instances when Gmail seems to take an eternity to send an email. This happens usually when you are sending a large file as an attachment with the email, but that’s not the only situation when Gmail seems to be frustratingly slow. It could be slow server too which isn’t that common considering the way Gmail has worked in the recent past.
So, Gmail team realized that having to wait for a mail to be sent and have that process hijack your entire email account isn’t a good feeling, and hence you now have a new feature called Background Send. As the name indicates, this will help Gmail send the email in background while you carry on with your other email related activities.
Background Send is currently part of Gmail Labs so you’ll first need to enable it from the Labs settings. If Gmail is not able to send your message for some reason, it will notify you and provide the links to fix it at that time or at a later time.
As you see in the screenshot above, the notification is in dark red color to make sure that it doesn’t goes unnoticed.
Overall, I personally feel that this was a much needed feature. I have to admit though that I never realized that a feature like this could exist. I just felt that Gmail sending process needs to be faster (which it definitely should). But if for some reason it has to take its own time to send the message, at least this feature would allow us to get some work done in that time.