give me some idea....to email verification code to customers email ID when they sign in

Answer 1

Yuo will have to take permit by google
To access database

Answer 2

you can also use javascript for email verification

Answer 3

After the user send the registration, you will have to generate a single id (php function rand()) then use the PHP fonction mail(). In the arguments you send the href including the id

Answer 4

send them activation href to email