Examples of using the caldera_forms_mailer filter. See https://calderaforms.com/doc/caldera_forms_mailer/

attach-file.php

<?php
add_filter( 'caldera_forms_mailer', function( $mail, $data, $form ) {
	//MAKE SURE TO CHANGE FORM ID
	if( 'CF1243hiMatt' == $form[ 'ID' ] ) {
		//$data has all of the field data for submission

		//change this to your field ID
		$field_id = 'cf1234hiKevin';
		if(  ! empty( $data[ $field_id ] ) ){
			//create temporary file, see: http://php.net/manual/en/function.tmpfile.php
			$temp_file = tmpfile();
			//write field value to that file
			fwrite( $temp_file, $data[ $field_id ] );
			$mail[ 'attachments' ][] = $temp_file;
		}
	}

	return $mail;

}, 10, 3 );

change-message.php

<?php
add_filter( 'caldera_forms_mailer', function( $mail, $data, $form ) {
  //MAKE SURE TO CHANGE FORM ID
  if( 'CF1243..' == $form[ 'ID' ] ) {
    //$data has all of the field data for submission
    //Presuming that fld1235 is name.
    //Presuming that fld54321 has a post ID for a post with useful meta data, like a phone number for a store location.
    $name = $data[ 'fld1235' ];
    $id = $data[ 'fld54321' ];
    $phone_number = get_post_meta( $id, 'phone_number', true );
    $message = "Thanks for getting in touch {$name} we will get back to you soon. If you have immediate questions, the phone number for our closest store is {$phone_number}.";
    $mail[ 'message' ] = $message;
  }

  return $mail;

}, 10, 3 );

change-recipient.php

<?php
add_filter( 'caldera_forms_mailer', function( $mail, $data, $form ) {
  //MAKE SURE TO CHANGE FORM ID
  if( 'CF1243..' == $form[ 'ID' ] ) {
    $mail[ 'recipients' ][] = 'luke@skywalker.com';
  }

  return $mail;

}, 10, 3 );