Here is the comment i left today on GSoc Wojtek Szkutnik project
There are 3 types of mails in WordPress
- the multi site related (not pluggable)
- the blog related (pluggable)
- the retrieve password mail (hookable [wp-login.php:233])
Don’t you think that WordPress needs a big code review to have a unique way to handle/process mail and to make them all pluggable or hookable ?