Last August, I described how to. In that post, I bemoaned the lack of a similar feature in Gmail. Well, Google engineer Yuzo Fujishima comes to the rescue with a new tool called Undo Send, though unlike Outlook's send-delay feature, in Gmail, you have to act--or unact--fast.
To activate the feature, open Gmail, click Settings in the top-right corner, and choose the Labs tab. If you don't see a Labs tab, click more in the top-left menu, select even more, click the Labs link at the top right, choose Gmail Labs. Scroll to Undo Send, click Enable, and select Save Changes.
This feature isn't a miracle worker; it can pull back a message only in the first 5 seconds after you click Send. Still, many an e-mail "Oops!" comes to mind in that split second after you send it.
The Undo option appears for about 5 seconds in the "Your message has been sent" message at the top of your in-box.
If you click Undo in time, your message is yanked from the outbound queue and you see a message informing you that the send was undone.
Clearly, the Gmail Undo Send feature doesn't give you anywhere near the level of control you get when delaying sent messages in Outlook, but Gmail's version is much simpler to implement.
The Send Later extension for the Mozilla Foundation's Thunderbird e-mail client provides a similar function. Unfortunately, several people report problems using Send Later with the latest version 18.104.22.168 of Thunderbird. The extension appeared to work as advertised on my Vista PC, however.
To activate Send Later, press Ctrl-Shift-Enter when you've finishing composing the message. In the "Send this email later" dialog box that opens, select the time you want the message sent using the drop-down menus at the top of the window, or click one of the three preset delays: 15 minutes, 30 minutes, or 2 hours.
If only everything we do on a computer had a "do-over" button!