WordPress How To: Change the Email FROM Header | http://www.satoripress.com/2011/10/wordpress/plugin-development/change-the-email-from-header-56/

find_filters

ericteubert: ~/Sites/wordpress-single 
➜ awk 'NR >= 271 && NR <= 514' wp-includes/pluggable.php | grep apply_filters 
	extract( apply_filters( 'wp_mail', compact( 'to', 'subject', 'message', 'headers', 'attachments' ) ) );
	$phpmailer->From     = apply_filters( 'wp_mail_from'     , $from_email );
	$phpmailer->FromName = apply_filters( 'wp_mail_from_name', $from_name  );
	$content_type = apply_filters( 'wp_mail_content_type', $content_type );
	$phpmailer->CharSet = apply_filters( 'wp_mail_charset', $charset );

find_wp_mail

ericteubert: ~/Sites/wordpress-single 
➜ ack "function wp_mail"
wp-includes/pluggable.php
271:function wp_mail( $to, $subject, $message, $headers = '', $attachments = array() ) {

functions.php

<?php
function set_mail_header_from( $from ) {
	return "silence@satoripress.com";
}
add_filter( 'wp_mail_from', 'set_mail_header_from' );

function set_mail_header_from_name( $from_name ) {
	return "SATORIPRESS | Random WordPress Insights";
}
add_filter( 'wp_mail_from_name', 'set_mail_header_from_name' );

functions_5.3.php

<?php
add_filter( 'wp_mail_from', function ( $from ) {
	return "silence@satoripress.com";
} );

add_filter( 'wp_mail_from_name', function ( $from_name ) {
	return "SATORIPRESS | Random WordPress Insights";
} );

pluggable.php

<?php	
/**
 * Send mail, similar to PHP's mail
 *
 * [...]
 * 
 * @uses apply_filters() Calls 'wp_mail' hook on an array of all of the parameters.
 * @uses apply_filters() Calls 'wp_mail_from' hook to get the from email address.
 * @uses apply_filters() Calls 'wp_mail_from_name' hook to get the from address name.
 * @uses apply_filters() Calls 'wp_mail_content_type' hook to get the email content type.
 * @uses apply_filters() Calls 'wp_mail_charset' hook to get the email charset
 * @uses do_action_ref_array() Calls 'phpmailer_init' hook on the reference to
 *		phpmailer object.
 *
 * [...]
 *
 */