on both desktop and mobile systems.

Both systems have a rather short time period

where you can unsend your message,

but it is possible.

First, you need to set the time limit

for undoing a message send.

Click on settings, the small gear icon.

And then click on "See all settings."

In the "Undo Send" section,

select the send cancellation period time.

You can choose between five, 10,

20, or 30 seconds.

Then scroll to the bottom of the page

and click "Save Changes."

Now, as soon as you send an email,

look for the "Message sent" pop-up,

which will appear in the lower-left side of your screen.

You'll have the option to undo or view your message.

Click "Undo." The message will unsend,

and a window to recompose the message

will appear in the bottom-right side of the screen.

The process to unsend an email in Gmail

on an iPhone, iPad, or Android device

is basically the same,

the difference being

that you do not have the option

to change the length of the cancellation period.

It is set to an unchangeable five seconds,

so you must act quickly.

After you send an email,

a sent notification will appear

at the bottom of the screen alongside an undo option.

Tap "Undo." The message will unsend,

and you'll be taken to a screen

to recompose the message.