Change record status: 
Project: 
Introduced in branch: 
7.x
Introduced in version: 
7.12
Description: 

Functions implementing hook_mail_alter() may have reason to cancel sending by the drupal_mail() function. Formerly, this was done by setting $message['To'] to an invalid address. Now they may set $message['send'] = FALSE to accomplish the same goal in a cleaner way.

Impacts: 
Module developers