How to add Email field in Checkout page and sending E-mail in Drupal Commerce? I did cart using "commerce_kickstart-7.x-2.4-core" module. I would like to add "Email Id" field when doing a checkout. Actually I need that If user provides different email Id's rather than registered mail-id in "BILLING INFORMATION" and "SHIPPING INFORMATION" then after completion of Checkout process, the product payment details should send mail to those E-mail Id's.

Rules export

{ "rules_check_order_for_billing_information_mail" : {
    "LABEL" : "Check order for Billing information Mail",
    "PLUGIN" : "reaction rule",
    "REQUIRES" : [ "rules", "commerce_checkout" ],
    "ON" : [ "commerce_checkout_complete" ],
    "DO" : [
      { "entity_create" : {
          "USING" : {
            "type" : "commerce_customer_profile",
            "param_type" : "billing",
            "param_user" : [ "site:current-user" ]
          },
          "PROVIDE" : { "entity_created" : { "entity_created" : "Created entity" } }
        }
      },
      { "mail" : {
          "to" : [ "entity-created:field-billing-email" ],
          "subject" : "Test Subject for Billing mail",
          "message" : "Test Message for Billing mail",
          "language" : [ "" ]
        }
      }
    ]
  }
}
I believe you are using Customer Profile for asking customer billing and shipping address. 


So navigate to 
Store->Customer profiles->Profile types->Billing/Shipping Information->Manage fields.
Add one more fields in there for email &amp; make that mandatory.
Add a checkout rules, put condition like "Entity has field" &amp; check your added field.
Add a action "Send mail" and select your added field in TO field &amp; organize your template using tokens of commerce-order.


I hope this will work, though there are other way working around code.