How do i generate token for each user they submit my custom form?
1.Declare custom tokens using hook_token_info()


2.Create custom tokens using hook_tokens()



3.You can use your custom tokens using token_replace()
that is call the token_replace at the place where u need to send the email.

4.Create a seperate file inside your module with .tokens.inc extension and include the hook_tokens_info() and hook_tokens() inside it.