Steps to Recall Sent Email in gmail

Step 1- Login Gmail Account

Step 2 – Click on Setting

Step 3 – Click on All Setting

Step 4 – Go to Undo Sent option Your will see default undo time of mail is 5 second.

Step 5- Increase 10 or 20 second undo time and scroll down the page and click on save button.

Now your When you send email you will see the undo button after send email till 20 second. click click on undo to Rcall your Sent Email

See Time Setting in below Snapshot