WSOD when mail_api is installed in sites/all

When mail_api is installed in sites/all, it breaks the entire site with an error message:

Fatal error: require_once() [function.require]: Failed opening required 'mail_api.hooks.inc' (include_path='.:/usr/share/php:/usr/share/pear') in /my_site_path/sites/default/modules/mail_api/mail_api.module on line 103

Vianney Stroebel
Likwid - Spécialistes Drupal - Paris