how to undo a send mail in gmail within 30 sec

Hi friend 

i am again here with a fabulous trick which will help you to undo a send mail in gamil with in 30 sec 

first go to www.gmail.com and login with your gmail id and password 

now click on gmail setting 

 now click on labs in setting 

now search for a lab "undo"

now click on enable 

 

no click on save changes 

 

now you are done..

well lets come and check its work 

compose a mail to anyone 

now send it 

when you will send ,you will get a notification like it 

you will see undo 

than click on it and your mail sending will be undo like it 

you had done...

cheers!!!!!!!