Add this one to the annals of "What took you so long Google?" Gmail's greatest feature just graduated from the service's experimental labs to become a regular part of Gmail: Undo Send. With this feature enabled, you have a pre-determined number of seconds to recall the email you just sent.
If you've never used this feature, I can't stress enough how helpful it is. We've all sent emails we didn't mean to or had second thoughts about the wording. Prior to Undo Send, we just had to suck it up and live with our mistakes. Not a great situation to be in when email is such a critical communication tool--even in this era of HipChat and Slack.
Overnight success, six years ago
Undo Send began as an experimental feature in 2009 when it offered only a five second retrieval period. It was a hit almost immediately and has been a mainstay of many Gmail accounts since it was first introduced.
Although handy, Undo Send does have limits beyond the recall grace period. Once you click Send on an email, an undo option appears at the top of your inbox or whatever page you're on in Gmail such as sent mail. Once you leave that page, the Undo Send option immediately disappears regardless of the grace period setting. In other words, when you want to use this option don't click anything until you've hit that Undo link.
Undo Send's graduation into standard Gmail comes less than a month after Google added the feature to Inbox by Gmail.
The impact on you at home: If you're already an Undo Send user then your current settings won't be affected. Everything will work as it should. Anyone who's new to the feature will find it under Settings > General. Undo Send allows you to recall an email either 5, 10, 20, or 30 seconds after you've hit Send. I'd recommend the maximum to be extra cautious, but if you like to live on the wild side, 5 or 10 seconds will work just fine.