add custom field to order confirmation email , from external file

[Oscar Mejia]

Greetings community, the details that what happens.

I created my personalized payment module, which applies a credit card.

When doing the trax, it returns the data of the transaction to an external file called "callback.php".

So, what I want is that data that I have in the file callback.php, show them in the mail of complete order, which reaches the user.

So that the user or the user has a backup of the data of their purchase and transaction.

I hope I was clear.

thanks for your help