How to pass extra params inside option hash in confirmation email in Rails?

I am trying to pass extra params inside the options{} hash in the confirmation email but It is just showing me subject and from headers in the mailer. This is my code

CustomMailer.confirmation_instructions(user,token, {custom_param: "abc"})

When I show opts data inside template like this

@first_name = opts

It shows

{:subject=>"Email Confirmation", :from=>"no-reply@sample.com"}

why it is not working?

any help?