I noticed a problem running a postie_post_after filter when the emails are fetched via get_mail.php.
I use Postie 1.5.16 with WP 3.6.1 to post emails from a gmail account every hour. The cron job runs a wget calling the get_mail.php program.
The filter is meant to setup language variables for another plugin (ceceppa multilanguage).
Anyway, when I run postie from the "Run Postie" button, the filter runs properly. The other postie_post_before filters run perfectly in both cases.
Do you have any idea?