Send pdf attached emails on form submit webform

I want to send a pdf file to each email after the form submit. I don’t want to generate a pdf, I want to send the pdf file I already have. Can anyone please help with this? I am using the webform module to create forms. I have three fields on the form, Firstname, Lastname, and Email. I want to send an email with an attached pdf to each email entered on the form submission.